3,650 research outputs found

    Advanced modeling for small glass furnaces

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    One of the most pressing issues facing the glass industry is improving energy efficiency. The largest energy user in any glass company is the melting furnace or furnaces. While large float glass and container glass companies have developed sophisticated control systems, little work has been done until recently for small glass furnaces. This thesis extends the work of Holladay (2005), in which an observer was developed to estimate the temperature of glass in a small day-tank furnace. The current work eliminates the assumption of homogeneous glass melt and refractory temperatures, and develops a furnace model suitable for implementation with a real-time controller.;A state space model of an end-fired furnace was developed in which the furnace was divided longitudinally into two zones. Zone 1 contains the burner flame cylinder , while Zone 2 is beyond the end of the flame cylinder. Separate states are identified for the temperatures of the refractory in the crown, the walls above the glass melt, the walls adjacent to the two primary melt zones, and the floor of the furnace. The furnace ends are also divided into similar zones constituting discrete states. The glass melt itself contains a thin, surface layer and two thicker layers of stratification. In all, 24 state variables are included in the model. The inputs are the net thermal power provided by the flame and the ambient temperature.;Simulations were performed in Simulink and Matlab and were used to predict the temperatures of all 24 state variables. The results were verified using data collected from a similar tank furnace at Fenton Art Glass Company. The results showed a significant stratification in the vertical axis of the furnace but very nearly uniform temperatures in the length and width directions. The model was used to study various melting strategies. Preliminary results suggest that using the estimated glass temperature and feedback from thermocouples in the wall and floor of the furnace could lead to significant energy savings in the melt cycle. Suggestions are made for using the model within a real-time control system implementable on a small glass furnace

    SARS-CoV-2 infection in pregnancy: A systematic review and meta-analysis of clinical features and pregnancy outcomes.

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    Background: Perform a systematic review and meta-analysis of SARS-CoV-2 infection and pregnancy. Methods: Databases (Medline, Embase, Clinicaltrials.gov, Cochrane Library) were searched electronically on 6th April and updated regularly until 8th June 2020. Reports of pregnant women with reverse transcription PCR (RT-PCR) confirmed COVID-19 were included. Meta-analytical proportion summaries and meta-regression analyses for key clinical outcomes are provided. Findings: 86 studies were included, 17 studies (2567 pregnancies) in the quantitative synthesis; other small case series and case reports were used to extract rarely-reported events and outcome. Most women (73.9%) were in the third trimester; 52.4% have delivered, half by caesarean section (48.3%). The proportion of Black, Asian or minority ethnic group membership (50.8%); obesity (38.2%), and chronic co-morbidities (32.5%) were high. The most commonly reported clinical symptoms were fever (63.3%), cough (71.4%) and dyspnoea (34.4%). The commonest laboratory abnormalities were raised CRP or procalcitonin (54.0%), lymphopenia (34.2%) and elevated transaminases (16.0%). Preterm birth before 37 weeks' gestation was common (21.8%), usually medically-indicated (18.4%). Maternal intensive care unit admission was required in 7.0%, with intubation in 3.4%. Maternal mortality was uncommon (~1%). Maternal intensive care admission was higher in cohorts with higher rates of co-morbidities (beta=0.007, p<0.05) and maternal age over 35 years (beta=0.007, p<0.01). Maternal mortality was higher in cohorts with higher rates of antiviral drug use (beta=0.03, p<0.001), likely due to residual confounding. Neonatal nasopharyngeal swab RT-PCR was positive in 1.4%. Interpretation: The risk of iatrogenic preterm birth and caesarean delivery was increased. The available evidence is reassuring, suggesting that maternal morbidity is similar to that of women of reproductive age. Vertical transmission of the virus probably occurs, albeit in a small proportion of cases. Funding: N/A

    Predictors of vitamin D status and its association with parathyroid hormone in young New Zealand children.

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    BACKGROUND: Despite increased awareness of the adverse health effects of low vitamin D status, few studies have evaluated 25-hydroxyvitamin D [25(OH)D] status in young children. OBJECTIVES: We aimed to assess vitamin D status on the basis of 25(OH)D and its relation with parathyroid hormone (PTH) and to identify possible predictors of 25(OH)D status in young children living in a country with minimal vitamin D fortification. DESIGN: Serum 25(OH)D and PTH concentrations were measured in a cross-sectional sample of children aged 12-22 mo [n = 193 for 25(OH)D, n = 144 for PTH] living in Dunedin, New Zealand (latitude: 45 degrees S). Anthropometric, dietary, and sociodemographic data were collected. RESULTS: The majority of children sampled in the summer (94%; 47 of 50) had 25(OH)D >50 nmol/L; however, nearly 80% of children sampled in the winter (43 of 55) had serum concentrations 60-65 nmol/L, a plateau in PTH was evident. CONCLUSIONS: Seasonal variation in 25(OH)D concentration implies that postsummer vitamin D stores were insufficient to maintain status >50 nmol/L year-round. Examination of the predictors of 25(OH)D in our model shows few modifiable risk factors, and thus effective dietary strategies may be required if future research determines that children with 25(OH)D concentrations <50 nmol/L are at significant health risk. This trial was registered at www.actr.org.au as ACTRN12605000487617

    Left gaze bias in humans, rhesus monkeys and domestic dogs

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    While viewing faces, human adults often demonstrate a natural gaze bias towards the left visual field, that is, the right side of the viewee’s face is often inspected first and for longer periods. Using a preferential looking paradigm, we demonstrate that this bias is neither uniquely human nor limited to primates, and provide evidence to help elucidate its biological function within a broader social cognitive framework. We observed that 6-month-old infants showed a wider tendency for left gaze preference towards objects and faces of different species and orientation, while in adults the bias appears only towards upright human faces. Rhesus monkeys showed a left gaze bias towards upright human and monkey faces, but not towards inverted faces. Domestic dogs, however, only demonstrated a left gaze bias towards human faces, but not towards monkey or dog faces, nor to inanimate object images. Our findings suggest that face- and species-sensitive gaze asymmetry is more widespread in the animal kingdom than previously recognised, is not constrained by attentional or scanning bias, and could be shaped by experience to develop adaptive behavioural significance

    Evaluation of Oxfendazole, Praziquantel and Albendazole against Cystic Echinococcosis: A Randomized Clinical Trial in Naturally Infected Sheep

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    Cystic Echinococcosis (CE) is a near-cosmopolitan parasitic zoonosis that causes economic losses in many regions of the world. This parasitic infection can be regarded as an emerging or re-emerging disease causing considerable losses in livestock production. CE is produced by the larval cystic stage (hydatid) of the dog parasite Echinococcus granulosus. After infective eggs are ingested, cysts develop mainly in lungs and liver of humans and animals (sheep, cattle, pigs, horses, etc). Infected people may require surgery and/or Albendazole-based chemotherapy. In this study, we evaluated the effects of Oxfendazole alone (an antiparasitic drug used in animals), Oxfendazole plus Praziquantel, and Albendazole plus Praziquantel against hydatid cysts in sheep over 4 to 6 weeks of treatment. All of the treatments in this study were efficacious in killing the larval stages and, therefore, in minimizing the risk of a dog acquiring new infections (taenias). These treatment schemes can be added to control measures in animals and eventually could be used for the treatment of human infection. Further investigations on different schedules of monotherapy or combined chemotherapy are needed, as well as studies to evaluate the safety and efficacy of Oxfendazole in humans

    Effects of fear factors in disease propagation

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    Upon an outbreak of a dangerous infectious disease, people generally tend to reduce their contacts with others in fear of getting infected. Such typical actions apparently help slow down the spreading of infection. Thanks to today's broad public media coverage, the fear factor may even contribute to prevent an outbreak from happening. We are motivated to study such effects by adopting a complex network approach. Firstly we evaluate the simple case where connections between individuals are randomly removed due to fear factor. Then we consider a different case where each individual keeps at least a few connections after contact reduction. Such a case is arguably more realistic since people may choose to keep a few social contacts, e.g., with their family members and closest friends, at any cost. Finally a study is conducted on the case where connection removals are carried out dynamically while the infection is spreading out. Analytical and simulation results show that the fear factor may not easily prevent an epidemic outbreak from happening in scale-free networks. However, it significantly reduces the fraction of the nodes ever getting infected during the outbreak.Comment: 19 pages, 10 figure

    High-E_T dijet photoproduction at HERA

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    The cross section for high-E_T dijet production in photoproduction has been measured with the ZEUS detector at HERA using an integrated luminosity of 81.8 pb-1. The events were required to have a virtuality of the incoming photon, Q^2, of less than 1 GeV^2 and a photon-proton centre-of-mass energy in the range 142 < W < 293 GeV. Events were selected if at least two jets satisfied the transverse-energy requirements of E_T(jet1) > 20 GeV and E_T(jet2) > 15 GeV and pseudorapidity requirements of -1 < eta(jet1,2) < 3, with at least one of the jets satisfying -1 < eta(jet) < 2.5. The measurements show sensitivity to the parton distributions in the photon and proton and effects beyond next-to-leading order in QCD. Hence these data can be used to constrain further the parton densities in the proton and photon.Comment: 36 pages, 13 figures, 20 tables, including minor revisions from referees. Accepted by Phys. Rev.
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