457 resultados para Carnauba wax
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Various studies have demonstrated that the stable hydrogen isotopic composition (dD) of terrestrial leaf waxes tracks that of precipitation (dDprecip) both spatially across climate gradients and over a range of different timescales. Yet, reconstructed estimates of dDprecip and corresponding rainfall typically remain largely qualitative, due mainly to uncertainties in plant ecosystem net fractionation, relative humidity, and the stability of the amount effect through time. Here we present dD values of the C31n-alkane (dDwax) from a marine sediment core offshore the Northwest (NW) African Sahel covering the past 100 years and overlapping with the instrumental record of rainfall. We use this record to investigate whether accurate, quantitative estimates of past rainfall can be derived from our dDwax time series. We infer the composition of vegetation (C3/C4) within the continental catchment area by analysis of the stable carbon isotopic composition of the same compounds (d13Cwax), calculated a net ecosystem fractionation factor, and corrected the dDwax time series accordingly to derive dDprecip. Using the present-day relationship between dDprecip and the amount of precipitation in the tropics, we derive quantitative estimates of past precipitation amounts. Our data show that (a) vegetation composition can be inferred from d13Cwax, (b) the calculated net ecosystem fractionation represents a reasonable estimate, and (c) estimated total amounts of rainfall based on dDwax correspond to instrumental records of rainfall. Our study has important implications for future studies aiming to reconstruct rainfall based on dDwax; the combined data presented here demonstrate that it is feasible to infer absolute rainfall amounts from sedimentary dDwax in tandem with d13Cwax in specific depositional settings.
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Aims 1 To identify the 3D soft tissue volumetric and linear landmark changes following treatment with the Twin-Block Appliance TBA. 2 To estimate the TBA treatment outcome on the soft tissue facial profile volumetric and linear landmark changes from the Postured Wax Bite (PWB). 3 To identify if there is any association between certain soft tissue landmark variables and successful treatment outcome of the TBA as measured by the reduction in overjet. 4 To assess the effects of TBA treatment on facial expressions. Materials and Methods Forty-seven Caucasian subjects with Class II division 1 were recruited. 3D images captured of each subject, pre-treatment (T1), with the PWB (T2) and at the end of treatment (T3). Soft tissue volumetric and linear changes as well as the correlation between facial parameters and successful treatment were calculated. Results The mean soft tissue volumetric change from T1 to T3 was 22.24 ± 16.73 cm³. Soft tissue profile linear changes from T1-T3 for lower facial landmarks were 4-5 mm. From T1-T3, the mean soft tissue volumetric change of the total sample was 60% of the change produced by the PWB (T1 to T2). Correlations were weak for all 3D facial parameters and successful overjet reduction. Facial expression changes were only significant for the lower landmarks. Conclusions 1 TBA treatment, in growing subjects, increased the lower facial soft tissue volume and caused forward movement of the lower soft tissue facial profile landmarks.2 The PWB can be used to estimate the treatment outcome of the TBA on soft tissue profile changes.3 No association was found between soft tissue landmark variables and successful overjet reduction.4 TBA treatment had no effect on the upper facial landmarks for each facial expression but it changed the lower facial expressions significantly except for maximal smile in males.
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The dominant forcing factors for past large-scale changes in vegetation are widely debated. Changes in the distribution of C4 plants-adapted to warm, dry conditions and low atmospheric CO2 concentrations (Collatz et al., 1998, doi:10.1007/s004420050468) -have been attributed to marked changes in environmental conditions, but the relative impacts of changes in aridity, temperature (Pagani et al., 1999, doi:10.1126/science.285.5429.876; Huang et al., 2001, doi:10.1126/science.1060143) and CO2 concentration (Cerling et al., 1993, doi:10.1038/361344a0; Kuypers et al., 1999, doi:10.1038/20659) are not well understood. Here, we present a record of African C4 plant abundance between 1.2 and 0.45 million years ago, derived from compound-specific carbon isotope analyses of wind-transported terrigenous plant waxes. We find that large-scale changes in African vegetation are linked closely to sea surface temperatures in the tropical Atlantic Ocean. We conclude that, in the mid-Pleistocene, changes in atmospheric moisture content - driven by tropical sea surface temperature changes and the strength of the African monsoon - controlled aridity on the African continent, and hence large-scale vegetation changes.
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A transect of marine surface sediment samples from 1° N to 28° S off southwest Africa was analysed to verify the application of hydrogen isotope compositions of terrestrial plant-wax n-alkanes preserved in ocean sediments as a proxy for continental hydrological conditions. Conditions on the adjacent continent range from humid evergreen forests to deciduous forests, wood- and shrub land and further to arid grasslands and deserts. The hydrogen isotope values for the dominant n-alkane homologues (C29, C31 and C33) vary from -123 per mil to -141 per mil VSMOW and correlate with the modelled hydrogen isotope composition of mean annual and growing season precipitation of postulated continental source areas (r up to 0.8, p < 0.01). The apparent hydrogen isotope fractionation between alkanes and mean annual precipitation is remarkably uniform (-109 per mil on average, Sigma <= 5 per mil, n = 27). Potentially, effects of aridity on the apparent hydrogen isotope fractionation are concealed by the contribution of different plants (C3 dicotyledons vs C4 grasses). Thus, isotope ratios of leaf wax n-alkanes preserved in ocean margin sediments in these and similar tropical regions may be directly converted to dD ratios of ancient precipitation by employing a constant hydrogen isotope fractionation.
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We present a Younger Dryas-Holocene record of the hydrogen isotopic composition of sedimentary plant waxes (dDwax) from the southern European Alps (Lake Ghirla, N-Italy) to investigate its sensitivity to climatic forcing variations in this mid-latitude region (45°N). A modern altitudinal transect of dD values of river water and leaf waxes in the Lake Ghirla catchment is used to test present-day climate sensitivity of dDwax. While we find that altitudinal effects on dDwax are minor at our study site, temperature, precipitation amount, and evapotranspiration all appear to influence dDwax to varying extents. In the lake-sediment record, dDwax values vary between -134 and -180 per mil over the past 13 kyr. The long-term Holocene pattern of dDwax parallels the trend of decreasing temperature and is thus likely forced by the decline of northern hemisphere summer insolation. Shorter-term fluctuations, in contrast, may reflect both temperature and moisture-source changes. During the cool Younger Dryas and Little Ice Age (LIA) periods we observe unexpectedly high dDwax values relative to those before and after. We suggest that a change towards a more D-enriched moisture source is required during these intervals. In fact, a shift from northern N-Atlantic to southern N-Atlantic/western Mediterranean Sea sources would be consistent with a southward migration of the Westerlies with climate cooling. Prominent dDwax fluctuations in the early and middle Holocene are negative and potentially associated with temperature declines. In the late Holocene (<4 kyr BP), excursions are partly positive (as for the LIA) suggesting a stronger influence of moisture-source changes on dDwax variation. In addition to isotopic fractionations of the hydrological cycle, changes in vegetation composition, in the length of the growing season, and in snowfall amount provide additional potential sources of variability, although we cannot yet quantitatively assess these in the paleo-record. We conclude that while our dDwax record from the Alps does contain climatic information, it is a complicated record that would require additional constraints to be robustly interpreted. This also has important implications for other water-isotope-based proxy records of precipitation and hydro-climate from this region, such as cave speleothems.
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A complete series of cross-sectional computed tomography (CT) scans were obtained of a mummy of an Egyptian priestess, Tjenmutengebtiu, (Jeni), who lived in the twenty-second Dynasty (c. 945-715 BC). The purpose of this joint British Museum and St. Thomas’ Hospital project was effectively to ‘unwrap’ a mummy using cross-sectional X-rays. Jeni is encased in a beautifully decorated anthropomorphic cartonnage coffin. The head and neck were scanned with 2mm slices, the teeth with 1mm slices and the rest of the body with 4 mm slices, a 512 x 512 matrix was used. The 2D CT images, and 3D surface reconstruction’s, demonstrate many features of the embalming techniques and funerary customs of the XXII Dynasty. The presence of cloth protruding from the nasal cavities into the otherwise empty cranial cavity indicates that the brain was extracted via the nose. The remains of the heart can be seen as well as four organ packs corresponding to the mummified and repackaged lungs, intestines, stomach and liver. Each of the organ packs encloses a wax figurine representing one of the four sons of Horus. The teeth are in very good condition with little signs of wear, which, considering the gritty diet of the Egyptians, indicates that Jeni must have been very young when she died. A young age of death is also suggested by analysis of the shape of the molar teeth. The body is generally in very good condition demonstrating the consummate skill of the twenty-second Dynasty embalmers.
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Independent Brisbane: Four Plays is, as the title suggests, a collection of plays by independent theatre-makers and theatre-making collectives in Brisbane in the 2002– 07 period, including Marcel Dorney’s Harriers (6–51), the nest’s The Knowing of Mary Poppins (52–102), Linda Hassall’s Post Office Rose (103–71) and Maxine Mellor’s Magda’s Fascination with Wax Cats (172–216). According to the contextualising information on the book’s back cover, these plays are ‘distinctive’ in content, story and style, ‘[y]et carry with them what is characteristic of the city they come from – a preoccupation with landscape, creation in tightly knit collaborative teams and brave, often unexpected, theatrical choices’.
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The formation of a venture relies, in part, upon the participants reaching a shared understanding of purpose and process. Yet in circumstances of great complexity and uncertainty how can such a shared understanding be created? If the response to complexity and uncertainty is to seek simplicity in order to find commonality then what is lost and what is at risk? Can shared understandings of purpose and process be arrived at by embracing complexity and uncertainty and if so how? These questions led us to explore the process of dialogue and communication of a team in its formative stages. Our interests were not centred upon the behavioural characteristics of the individuals in the 'forming' stage of group dynamics but rather the process of cognitive and linguistic turns, the wax and wan of ideas and, the formation of shared meaning. This process of cognitive and linguistic turns was focused thematically on the areas of foresight, innovation, entrepreneurship, and public policy. This cross disciplinary exploration sought to explore potential synergies between these domains, in particular in developing a conceptual basis for long term thinking that can inform wiser public policy.
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Purpose. To quantify the molecular lipid composition of patient-matched tear and meibum samples and compare tear and meibum lipid molecular profiles. Methods. Lipids were extracted from tears and meibum by bi-phasic methods using 10:3 tertbutyl methyl ether:methanol, washed with aqueous ammonium acetate, and analyzed by chipbased nanoelectrospray ionization tandem mass spectrometry. Targeted precursor ion and neutral loss scans identified individual molecular lipids and quantification was obtained by comparison to internal standards in each lipid class. Results. Two hundred and thirty-six lipid species were identified and quantified from nine lipid classes comprised of cholesterol esters, wax esters, (O-acyl)-x-hydroxy fatty acids, triacylglycerols, phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and phosphatidylserine. With the exception of phospholipids, lipid molecular profiles were strikingly similar between tears and meibum. Conclusions. Comparisons between tears and meibum indicate that meibum is likely to supply the majority of lipids in the tear film lipid layer. However, the observed higher mole ratio of phospholipid in tears shows that analysis of meibum alone does not provide a complete understanding of the tear film lipid composition.
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An in vivo murine vascularized chamber model has been shown to generate spontaneous angiogenesis and new tissue formation. This experiment aimed to assess the effects of common biological scaffolds on tissue growth in this model. Either laminin-1, type I collagen, fibrin glue, hyaluronan, or sea sponge was inserted into silicone chambers containing the epigastric artery and vein, one end was sealed with adipose tissue and the other with bone wax, then incubated subcutaneously. After 2, 4, or 6 weeks, tissue from chambers containing collagen I, fibrin glue, hyaluronan, or no added scaffold (control) had small amounts of vascularized connective tissue. Chambers containing sea sponge had moderate connective tissue growth together with a mild "foreign body" inflammatory response. Chambers containing laminin-1, at a concentration 10-fold lower than its concentration in Matrigel™, resulted in a moderate adipogenic response. In summary, (1) biological hydrogels are resorbed and gradually replaced by vascularized connective tissue; (2) sponge-like matrices with large pores support connective tissue growth within the pores and become encapsulated with granulation tissue; (3) laminin-containing scaffolds facilitate adipogenesis. It is concluded that the nature and chemical composition of the scaffold exerts a significant influence on the amount and type of tissue generated in this in vivo chamber model.
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Children are particularly susceptible to air pollution and schools are examples of urban microenvironments that can account for a large portion of children’s exposure to airborne particles. Thus this paper aimed to determine the sources of primary airborne particles that children are exposed to at school by analyzing selected organic molecular markers at 11 urban schools in Brisbane, Australia. Positive matrix factorization analysis identified four sources at the schools: vehicle emissions, biomass burning, meat cooking and plant wax emissions accounting for 45%, 29%, 16% and 7%, of the organic carbon respectively. Biomass burning peaked in winter due to prescribed burning of bushland around Brisbane. Overall, the results indicated that both local (traffic) and regional (biomass burning) sources of primary organic aerosols influence the levels of ambient particles that children are exposed at the schools. These results have implications for potential control strategies for mitigating exposure at schools.
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The subject of this work is the poetics of «The Wax Effigy», a short novel or novella by Jurii Tynianov, Russian writer, literary critic, historian of literature and prominent literary theoretician. The plot structure of the novel is based upon a real event, the creation by Bartolomeo Carlo Rastrelli in 1725 of a wax sculpture of the first Russian emperor, Peter the Great. «Construction of the Sham» consists of three chapters, an introduction and a conclusion. Due to the fact that Tynianov was at the same time a prose writer and theoretician of literature it seemed important to consider the reception of his prose and his works on literary theory in relationship to each other. The introduction is devoted to this task. The first chapter is about the history of the creation of the novel and its reception. Tynianov stopped writing one short story in order to write the novel; these two works have some common traits. It seems almost obvious that his work on the first text was a real step toward the creation of the second. In the first story there is an opposition of dead/alive which is semantic prefiguring of a central motif in «The Wax Effigy». An analysis of the reception of the novel demonstrated that almost every critic writing about the novel has described it as nonsense. Critics considered Tynianov's work in terms of «devices» and «content» and could not understand how devices are related to the content of the novel: the novel was thought as a signifier without any signified. Implicitly, critics thought the signified of the novel as a traditional one of the historical novel, as the historiosophical «idea», embodied in the system of literary devices. In this case literature becomes something instrumental, a kind of expression of extraliterary content. In contradistinction to that Tynianov considered literary semantics as an effect of the literary structure. From his point of view the literary sense is immanent to the process of signification accomplished inside the literary text. The second chapter is devoted to a rhetorical analysis of the opposition dead/alive. Tynianov systematically compares both terms of the opposition. As a result of this strategy the wax effigy of the dead emperor becomes «as if» alive and the world of living people «as if» dead. The qualifier «as if» refers to the fact that Tynianov creates an ambiguous semantic system. This rhetoric is related to European Romanticism and his «fantastic literature» (Merimé, Hoffmann, Maupassant etc.). But Tynianov demonstrates a linguistic origin of the strange fantoms created by romantics; he demystifies these idols by parodying the fantastic literature, that is, showing «how it was done». At the same time, the opposition mentioned above refers to his idea of «incongruity» which plays a prominent role in Tynianov s theory but has never been conceptualised. The incongruity is a inner collision of the literary text; from Tynianov's point of view the meaning of the work of literature is always a dynamic collision of semantically heterogeneous elements struggling with each other. In «The Wax Effigy» Tynianov creates a metalevel of the work demonstrating the process of creation of the literary sense. The third chapter is a reconstruction of Tynianov's conception of the historical prose, specifically of the mechanisms by which historical facts are transformed into literary events. Tynianov thought that the task of the historical novelist is to depict his hero as an actor, to demonstrate that as a wearer of many masks he is a creator of appearances, ambiguities. Here, in the «figure of fiction» (Andrei Belyi), the very idea of the historical prose and rhetoric employed in «The Wax Effigy», history and literature meet each other. In his last theoretical work, «On parody» Tynianov writes about the so-called sham structure of parody. In his opinion every parody is a text about other texts and «serious» work which could be read at the same time as a text about «reality». This twofold structure of parody is that of «The Wax Effigy»: that text speaks about ambiguities of the history and about ambiguities of the literary sense, about social reality of the past and - about the working of the literature itself. «The Wax Effigy» is written as a autoreflective text, as an experiment in literary semantics, as a system of literary ambiguities - of hero, rhetoric and the text itself. The meaning of the novel is created not by the embodiment extraliterary idea, but by the process of signification accomplished inside the work of literature. In this sense Tynianov's novel is parody, a break with the tradition of the historical novel preceding «The Wax Effigy».
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Reflection and transmission coefficients of rubberized coir pads over the frequency band 200 kHz to 4 MHz are presented in this Paper. These results are compared with those reported for neoprene, paraffin wax, rubber car mat and plastic door mat1. The rubberized coir pads were found to possess wideband absorption characteristics. It has been experimentally found that 0.05 m thick coir pads have almost 100% absorption in the frequency range 800 kHz-3 MHz with a maximum at 2.35 MHz. We have used this material for lining the water tank for underwater acoustic studies.
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Drop formation at the conical tips of melting rods has been experimentally studied using the transparent wax-alcohol/acetonitrile system. The effects of cone angle, rod diameter, immersion depth, and bath temperature on the detached drop mass have been studied over a wide range, besides recording useful qualitative information based on visual observation. The experimental results suggest that the phenomenon of drop formation at the tip of melting rods has a close parallel with the drop formation at conical tips, at least on a qualitative basis. However, the results could not be quantified owing to difficulties in characterizing the physical properties of the system, despite efforts to minimize them.
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Closed Systems was an exhibition of sculptural works held at MetroArts, Brisbane in the group exhibition 'Platform 2012' curated by Jan Manton. My contribution to the group show was a series of 13 bronze sculptures, produced using a lost-wax casting process. Each form was derived from a sapling that had been manipulated so that branches and roots were interconnected. The resulting 'looped' forms evoked notions on narcissism, self-absorption and introversion. The works were subsequently exhibited at the National Arts School in Sydney as part of the Kodak Minolta Art Prize (2013).