385 resultados para DISCRETE-SCALE-INVARIANCE
Laboratory and pilot scale pretreatment of sugarcane bagasse by acidified aqueous glycerol solutions
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Pretreatment of sugarcane bagasse with acidified aqueous glycerol solution was evaluated at both laboratory and pilot scales. Laboratory scale pretreatment (4.00 g dry mass in 40.00 g liquid) with glycerol solutions containing ≤ 20 wt% water and 1.2 wt% HCl at 130 °C for 60 min resulted in biomass having glucan digestibilities of ≥ 88%. Comparable glucan enzymatic digestibility of 90% was achieved with bagasse pretreated at pilot scale (10 kg dry mass in 60 kg liquid) using a glycerol solution containing 0.4 wt% HCl and 17 wt% water at 130 °C for 15 min. We attribute more efficient pretreatment at pilot scale (despite shorter reaction time and reduced acid content) to improved mixing and heat transfer in a horizontal reactor. Pretreatment of sugarcane bagasse with acid-catalysed glycerol solutions likely produces glycerol-glycosides, which together with hydrolysed lignin are potential substrates for the production of biopolymers.
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Background: Antibiotic overuse is influenced by several factors that can only be measured using a valid and reliable psychosocial measurement instrument. This study aims to establish translation and early stage validation of an instrument recently developed by this research team to measure factors influencing the overuse of antibiotics in children with upper respiratory tract infections in Saudi Arabia. Method: The content evaluation panel was composed of area experts approached using the Delphi Technique. Experts were provided with the questionnaires iteratively, on a three-round basis until consensus on the relevance of items was reached independently. Translation was achieved by adapting Brislin’s model of translation. Results: After going through the iterative process with the experts, consensus was reached to 58 items (including demographics). Experts also pointed out some issues related to ambiguity and redundancy in some items. A final Arabic version was produced from the translation process. Conclusion: This study produced preliminary validation of the developed instrument from the experts’ contributions. Then, the instrument was translated from English to Arabic. The instrument will undergo further validation steps in the future, such as construct validity.
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Background Antibiotics overuse is a global public health issue influenced by several factors, of which some are parent-related psychosocial factors that can only be measured using valid and reliable psychosocial measurement instruments. The PAPA scale was developed to measure these factors and the content validity of this instrument was assessed. Aim This study further validated the recently developed instrument in terms of (1) face validity and (2) construct validity including: deciding the number and nature of factors, and item selection. Methods Questionnaires were self-administered to parents of children between the ages of 0 and 12 years old. Parents were conveniently recruited from schools’ parental meetings in the Eastern Province, Saudi Arabia. Face validity was assessed with regards to questionnaire clarity and unambiguity. Construct validity and item selection processes were conducted using Exploratory factor analysis. Results Parallel analysis and Exploratory factor analysis using principal axis factoring produced six factors in the developed instrument: knowledge and beliefs, behaviours, sources of information, adherence, awareness about antibiotics resistance, and parents’ perception regarding doctors’ prescribing behaviours. Reliability was assessed (Cronbach’s alpha = 0.78) which demonstrates the instrument as being reliable. Conclusion The ‘factors’ produced in this study coincide with the constructs contextually identified in the development phase of other instruments used to study antibiotic use. However, no other study considering perceptions of antibiotic use had gone beyond content validation of such instruments. This study is the first to constructively validate the factors underlying perceptions regarding antibiotic use in any population and in parents in particular.
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Introduction To date, there has been little systematic, quantitative research on the links between academic pressure and mental health among adolescents in Asia, and none in Vietnam. In part, this is because of a lack of appropriate tools to measure this complex phenomenon. This study was to validate the Educational Stress Scale for Adolescents (ESSA), developed and tested in China, with the aim of fostering further research in Asia. Methods A total of 1283 students were recruited in 3 secondary schools and 3 high schools in Ho Chi Minh City, Vietnam. Anonymous, selfreport questionnaires included the ESSA and previously validated measures of mental health. Results Among the 1226 questionnaires available, 54% of respondents were female. The mean age was 15.3 years. Students reported substantial study burden. The ESSA had good internal consistency, and factorial validity and concurrent validity were established. Conclusion The ESSA is a suitable measure for school-based mental health research in Asia.
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Restoring a large-scale power system has always been a complicated and important issue. A lot of research work has been done on different aspects of the whole power system restoration procedure. However, more time will be required to complete the power system restoration process in an actual situation if accurate and real-time system data cannot be obtained. With the development of the wide area monitoring system (WAMS), power system operators are capable of accessing to more accurate data in the restoration stage after a major outage. The ultimate goal of the system restoration is to restore as much load as possible while in the shortest period of time after a blackout, and the restorable load can be estimated by employing WAMS. Moreover, discrete restorable loads are employed considering the limited number of circuit-breaker operations and the practical topology of distribution systems. In this work, a restorable load estimation method is proposed employing WAMS data after the network frame has been reenergized, and WAMS is also employed to monitor the system parameters in case the newly recovered system becomes unstable again. The proposed method has been validated with the New England 39-Bus system and an actual power system in Guangzhou, China.
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Self reported driving behaviour in the occupational driving context has typically been measured through scales adapted from the general driving population (i.e. the Manchester Driver Behaviour Questionnaire (DBQ)). However, research suggests that occupational driving is influenced by unique factors operating within the workplace environment, and thus, a behavioural scale should reflect those behaviours prevalent and unique within the driving context. To overcome this limitation, developed the Occupational Driver Behaviour Questionnaire (ODBQ) which utilises a relevant theoretical model to assess the impact of the broader workplace context on driving behaviour. Although the theoretical argument has been established, research is yet to examine whether the ODBQ or the DBQ is a more sensitive measure of the workplace context. As such, this paper identifies selected organisational factors (i.e. safety climate and role overload) as predictors of the DBQ and the ODBQ and compares the relative predictive value in both models. In undertaking this task, 248 occupational drivers were recruited from a community-oriented nursing population. As predicted, hierarchical regression analyses revealed that the organisational factors accounted for a significantly greater proportion of variance in the ODBQ than the DBQ. These findings offer a number of practical and theoretical applications for occupational driving practice and future research.
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Amphiphilic poly(ethylene glycol)-block-pol (dimethylsiloxane)-block-poly(ethylene glycol)(PEG-block-PDMS block-PEG) triblock copolymers have been successfully prepared via hydrosilylation using discrete and polydisperse PEG of various chain lengths. Facile synthesis of discrete PEG (dPEG) is achieved via systematic tosylation and etherification of lower glycols. Amphiphilicity of the dPEG block-PDMS-block-dPEG triblock copolymer is illustrated by dynamic light scattering (DLS) and measurement of the critical micelle concentration (CMC).
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In this presentation, renowned arts practitioner, Sean Mee, and Nigel Lavender, Executive Director of the Queensland Music Festival, talk about how community arts practice can be used to build cultural captial in communities, using examples such large-scale musicals such as The Road We're ON (Charleville) and Behind the Cand (Bowen), Mee and Lavender highlight the importance of community-driven narrative and particiaption.
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Phylogenetic inference from sequences can be misled by both sampling (stochastic) error and systematic error (nonhistorical signals where reality differs from our simplified models). A recent study of eight yeast species using 106 concatenated genes from complete genomes showed that even small internal edges of a tree received 100% bootstrap support. This effective negation of stochastic error from large data sets is important, but longer sequences exacerbate the potential for biases (systematic error) to be positively misleading. Indeed, when we analyzed the same data set using minimum evolution optimality criteria, an alternative tree received 100% bootstrap support. We identified a compositional bias as responsible for this inconsistency and showed that it is reduced effectively by coding the nucleotides as purines and pyrimidines (RY-coding), reinforcing the original tree. Thus, a comprehensive exploration of potential systematic biases is still required, even though genome-scale data sets greatly reduce sampling error.
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Analysis of fossils from cave deposits at Mount Etna (eastern-central Queensland) has established that a species-rich rainforest palaeoenvironment existed in that area during the middle Pleistocene. This unexpected finding has implications for several fields (e.g., biogeography/phylogeography of rainforest-adapted taxa, and the impact of climate change on rainforest communities), but it was unknown whether the Mount Etna sites represented a small refugial patch of rainforest or was more widespread. In this study numerous bone deposits in caves in north-east Queensland are analysed to reconstruct the environmental history of the area during the late Quaternary. Study sites are in the Chillagoe/Mitchell Palmer and Broken River/Christmas Creek areas. The cave fossil records in these study areas are compared with dated (middle Pleistocene-Holocene) cave sites in the Mount Etna area. Substantial taxonomic work on the Mount Etna faunas (particularly dasyurid marsupials and murine rodents) is also presented as a prerequisite for meaningful comparison with the study sites further north. Middle Pleistocene sites at Mount Etna contain species indicative of a rainforest palaeoenvironment. Small mammal assemblages in the Mount Etna rainforest sites (>500-280 ka) are unexpectedly diverse and composed almost entirely of new species. Included in the rainforest assemblages are lineages with no extant representatives in rainforest (e.g., Leggadina), one genus previously known only from New Guinea (Abeomelomys), and forms that appear to bridge gaps between related but morphologically-divergent extant taxa ('B-rat' and 'Pseudomys C'). Curiously, some taxa (e.g., Melomys spp.) are notable for their absence from the Mount Etna rainforest sites. After 280 ka the rainforest faunas are replaced by species adapted to open, dry habitats. At that time the extinct ‘rainforest’ dasyurids and rodents are replaced by species that are either extant or recently extant. By the late Pleistocene all ‘rainforest’ and several ‘dry’ taxa are locally or completely extinct, and the small mammal fauna resembles that found in the area today. The faunal/environmental changes recorded in the Mount Etna sites were interpreted by previous workers as the result of shifts in climate during the Pleistocene. Many samples from caves in the Chillagoe/Mitchell-Palmer and Broken River/Christmas Creek areas are held in the Queensland Museum’s collection. These, supplemented with additional samples collected in the field as well as samples supplied by other workers, were systematically and palaeoecologically analysed for the first time. Palaeoecological interpretation of the faunal assemblages in the sites suggests that they encompass a similar array of palaeoenvironments as the Mount Etna sites. ‘Rainforest’ sites at the Broken River are here interpreted as being of similar age to those at Mount Etna, suggesting the possibility of extensive rainforest coverage in eastern tropical Queensland during part of the Pleistocene. Likewise, faunas suggesting open, dry palaeoenvironments are found at Chillagoe, the Broken River and Mount Etna, and may be of similar age. The 'dry' faunal assemblage at Mount Etna (Elephant hole Cave) dates to 205-170 ka. Dating of one of the Chillagoe sites (QML1067) produced a maximum age for the deposit of approximately 200 ka, and the site is interpreted as being close to that age, supporting the interpretation of roughly contemporaneous deposition at Mount Etna and Chillagoe. Finally, study sites interpreted as being of late Pleistocene-Holocene age show faunal similarities to sites of that age near Mount Etna. This study has several important implications for the biogeography and phylogeography of murine rodents, and represents a major advance in the study of the Australian murine fossil record. Likewise the survey of the northern study areas is the first systematic analysis of multiple sites in those areas, and is thus a major contribution to knowledge of tropical Australian faunas during the Quaternary. This analysis suggests that climatic changes during the Pleistocene affected a large area of eastern tropical Queensland in similar ways. Further fieldwork and dating is required to properly analyse the geographical extent and timing of faunal change in eastern tropical Queensland.
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Recent advances in computational geodynamics are applied to explore the link between Earth’s heat, its chemistry and its mechanical behavior. Computational thermal-mechanical solutions are now allowing us to understand Earth patterns by solving the basic physics of heat transfer. This approach is currently used to solve basic convection patterns of terrestrial planets. Applying the same methodology to smaller scales delivers promising similarities between observed and predicted structures which are often the site of mineral deposits. The new approach involves a fully coupled solution to the energy, momentum and continuity equations of the system at all scales, allowing the prediction of fractures, shear zones and other typical geological patterns out of a randomly perturbed initial state. The results of this approach are linking a global geodynamic mechanical framework over regional-scale mineral deposits down to the underlying micro-scale processes. Ongoing work includes the challenge of incorporating chemistry into the formulation.
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Introduction: Lower limb function in hurdling is patently asymmetrical. The lead limb undertakes the preparatory and landing steps while the trail limb contends with the hurdle and recovery steps. Discrete loading profiles of these steps will reflect the asymmetrical function and may provide useful insight into injury mechanisms. A pilot study was undertaken to determine the loading profiles of the hurdle, landing and recovery steps of elite male hurdlers. Equivalent data for steps between hurdles, where the running action is more symmetrical, were used for the purpose of comparison, simultaneously minimising the confounding effect of speed. Methodology: In-shoe pressures were recorded (FScan, 200 Hz) for four elite male hurdlers while they completed a routine hurdle drill at a self-selected fast but sub-race speed. The drill comprised of three consecutive hurdles. Data for the hurdle, landing and recovery steps of the first and second hurdles, along with data for the running steps between hurdles 1 and 2, and 2 and 3, were used for the purpose of analysis. Peak pressures within 1cm2 masks were determined for the hallux, first, central and fifth metatarsals (T1, M1, M2–4 and M5 respectively). Peak pressure (kPa) and loading duration (ms) for the hurdle, landing and recovery steps are reported as a percentage of the respective limb-matched values for between-hurdle steps. Results/discussion: For between-hurdle steps, T1, M1 and M2–4 peak pressures were 312/357, 356/306 and 362/368 kPa, lead/trail limbs respectively. For the hurdle, landing and recovery steps, pressures at T1 and M1 increased. For T1 the increases were in the order of 17%, 36% and 8% (hurdle, landing and recovery steps, respectively) while the corresponding increases at M1 were 7%, 54% and 20%. Pressures at M2–4 were similar for all steps, while M5 loaded erratically. For the between-hurdle steps, the loading durations at T1, M1 and M2–4, were 160/162, 170/142 and 190/191 ms, respectively. For the landing step, loading duration decreased for T1, M1and M2–4 (−8%, −19% and −18%, respectively). In the hurdle step, loading duration decreased for the metatarsals but not for T1. Conclusions: The hurdling action leads to regional pressure increases that act for shorter durations in comparison to the between-hurdle running steps. These changes are most notable at the first metatarsal, a common site of foot injury.
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The validity of the Multidimensional School Anger Inventory (MSAI) was examined with adolescents from 5 Pacific Rim countries (N ¼ 3,181 adolescents; age, M ¼ 14.8 years; 52% females). Confirmatory factor analyses examined configural invariance for the MSAI’s anger experience, hostility, destructive expression, and anger coping subscales. The model did not converge for Peruvian students. Using the top 4 loaded items for anger experience, hostility, and destructive expression configural invariance and partial metric and scalar invariances were found. Latent means analysis compared mean responses on each subscale to the U.S. sample. Students from other countries showed higher mean responses on the anger experience subscale (ds ¼ .37–.73). Australian (d ¼ .40) and Japanese students (d ¼ .21) had significantly higher mean hostility subscale scores. Australian students had higher mean scores on the destructive expression subscale (d ¼ .30), whereas Japanese students had lower mean scores (d ¼ 2.17). The largest latent mean gender differences (females lower than males) were for destructive expression among Australian (d ¼ 2.67), Guatemalan (d ¼ 2.42), and U.S. (d ¼ 2.66) students. This study supported an abbreviated, 12-item MSAI with partial invariance. Implications for the use of the MSAI in comparative research are discussed.
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To date, the formation of deposits on heat exchanger surfaces is the least understood problem in the design of heat exchangers for processing industries. Dr East has related the structure of the deposits to solution composition and has developed predictive models for composite fouling of calcium oxalate and silica in sugar factory evaporators.
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A dual-scale model of the torrefaction of wood was developed and used to study industrial configurations. At the local scale, the computational code solves the coupled heat and mass transfer and the thermal degradation mechanisms of the wood components. At the global scale, the two-way coupling between the boards and the stack channels is treated as an integral component of the process. This model is used to investigate the effect of the stack configuration on the heat treatment of the boards. The simulations highlight that the exothermic reactions occurring in each single board can be accumulated along the stack. This phenomenon may result in a dramatic eterogeneity of the process and poses a serious risk of thermal runaway, which is often observed in industrial plants. The model is used to explain how thermal runaway can be lowered by increasing the airflow velocity, the sticker thickness or by gas flow reversal.