Perinatal Stroke in Australian Children

Background:More than half of all strokes in children occur during the perinatal period, with a global incidence of 25–40 per 100,000 live births. Aetiology is unclear, hampering prevention research. Diagnosis is often delayed, hindering intervention: first, because some risk factors are present in healthy infants, making at-risk differentiation difficult; second, because variable clinical presentations exist. The aims were to determine Australian birth prevalence, scrutinise risk factors, analyse clinical characteristics and outcomes. Methods: Six studies were conducted. First, a systematic review examined the placental risk factors for perinatal stroke and second, a retrospective audit ascertained placental histopathology in neonatal practices. Third, a systematic review examined prematurity as a risk factor. Fourth study analysed aetiology; fifth study assessed prevalence; and sixth study examined outcomes of perinatal stroke from a longitudinal prospective population-based case- controlled study. Results: Estimated birth prevalence of perinatal stroke in Australia was 9.6 cases per 100,000 live births per year. Independent risk factors were smoke exposure during pregnancy, 10-minute Apgar score <7, neonatal infection, and hypoglycaemia. Additional risk factors were emergency caesarean section, resuscitation at birth, and abnormal cord blood gas. Conclusive assumptions about the placenta were not possible, given the low frequencies of examination, inconsistent reporting, and the contribution of prematurity. However, thromboinflammatory placental changes were associated with perinatal stroke. Interestingly, 35% presented with pure respiratory symptoms including tachypnoea, apnoea, and cyanosis. Conclusions: This perinatal stroke research identified rates, independent risk factors, clinical profiles and outcomes, with 48% having neurological impairment. A high index of clinical suspicion and prospective collaborative studies are needed to identify high-risk infants

Growth analysis of short duration transplant Aus rice (Oryza sativa L. cv. Parija) under irrigated ecosystem

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural&nbsp;University, Mymensingh during April to July 2012 to examine the effect of plant spacing and&nbsp;nitrogen level on the growth performance of short duration transplant&nbsp;Aus&nbsp;rice (cv. Parija) under irrigated ecosystem. The experiment comprised four plants spacings&nbsp;viz.,&nbsp;20 cm × 20 cm, 20 cm × 15 cm, 20 cm × 10 cm and 15 cm × 15 cm and four nitrogen levels&nbsp;viz. 0, 35, 70 and 105 kg N ha-1. The experiment was laid out in a Randomized Complete Block Design with three replications. Morpho-physiological characters, of transplant&nbsp;Aus&nbsp;rice (cv.&nbsp;Parija) significantly influenced by spacing of planting, nitrogen level and their interaction. At 60 DAT, the highest plant height (80.68 cm) was obtained at 20 cm × 15 cm spacing fertilized with 70 kg N ha-1&nbsp;which was as good as 20 cm × 10 cm fertilizad with 35 kg N ha-1.&nbsp; The maximum number of tillers hill-1&nbsp;(15.16) was obtained at 20 cm × 20 cm spacing fertilized with 105 kg N ha-1which was statistically at par with 20 cm × 15 cmfertilized with 70 kg N ha-1.&nbsp; The highest total dry matter (8.92g) was obtained at the 20 cm × 15 cm spacing fertilized with higher dose of nitrogen (105 kg N ha-1) and at 45-60 DAT, the highest crop growth rate (3.34) was obtained at 15 cm × 15 cm spacing fertilized with 35 kg N ha-1&nbsp;while the lowest CGR (1.12) was recorded at the same spacing (15 cm × 15 cm) with control treatment. This study revealed that short duration transplant&nbsp;Aus&nbsp;rice cv. Parija can be cultivated at 20 cm × 15 cm or 15 cm × 15 cm spacing with 35 to 105 kg N ha-1&nbsp;for proper growth

Oxy-fuel fluidized bed combustion of Victorian brown coal

Coal contributes to almost forty percent of global power generation. As conventional coal-fired power generation technologies result in large CO2 emission, the pursuit for new technologies focuses on either reducing CO2 emission or that allows easier capture of the emitted CO2 from coal-fired power plants. Oxy-fuel fluidized bed (Oxy-FB) combustion is one such technology due to its ability to produce concentrated CO2 stream in the flue gas. This concentrated CO2 allows easier capture for subsequent transportation and storage. Other important benefits of this technology are the potential for using any type of fuel, and the ability to control SO2 and NOX emissions. Despite its perceived advantages over conventional technologies, very little is known about the applicability of Oxy-FB for brown coal. Brown coal accounts for 91% of Victoria’s current electricity needs. Since Victoria has an estimated reserve of over 500 years of brown coal at the current consumption rate, successful application of Oxy-FB can potentially result in environment friendly power generation in Victoria. This first-ever study investigates the Oxy-FB combustion using Victorian brown coal in a combined experimental and modelling approach. The research involves designing and commissioning of a 10 kWth fluidized bed rig, carrying out experiments in laboratory scale and bench scale equipment, and performing thermodynamic and process modelling. Laboratory scale experiments using single char particle were conducted to investigate the combustion characteristics of individual and large char particle under Oxy-FB conditions. Particle temperature was observed to be higher compared to bed temperature. Up to 48°C difference was noticed between the char particle temperature and the bed temperature using 15% (v/v) steam in oxy-fuel combustion atmosphere. The temperature of the char particle during Oxy-FB combustion has practical implication for agglomeration. The bench scale experiments were carried out to evaluate combustion efficiency, agglomeration characteristics, sulphation characteristics, carbonation characteristics, NOX (NO, NO2 and N2O) emission, SOX (SO2 and SO3) emission, and trace elements (Hg, Se, As and Cr) emissions during Oxy-FB combustion of Victorian brown coal. A high level of CO2 concentration (90-94% in dry flue gas), over 99% combustion efficiency and no bed agglomeration under oxy-fuel combustion conditions including those with the addition of steam at temperatures between 800°C and 900°C. Moreover, the measured NOX and SOX concentration levels in the flue gas are within the permissible limits for coal-fired power plants in Victoria. This implies that additional NOX and SOX removal systems may not be required with Oxy-FB combustion of Victorian brown coal. The gaseous mercury concentrations, however, are considerably higher under oxy-fuel combustion compared to air combustion suggesting that mercury removal system may be required to avoid corrosion in the CO2 separation units if CO2 capture and transportation is intended. These conventional pollutants and trace elements emission characteristics are of great importance for the design of the gas cleaning systems for CO2 capture and storage (CCS) purposes. Furthermore, these results also provide information for selecting the optimum operating condition. Thermodynamic equilibrium modelling was carried out to predict the compounds formed during the combustion of Victorian brown coal under different Oxy-FB combustion conditions. It was predicted that the amount of toxic gaseous Cr6+ species was greater for oxy-fuel combustion than for air combustion. The distribution of toxic Se4+ species, however, remained almost the same in both combustion conditions within the typical temperature range for Oxy-FB combustion (800 - 950°C). A process model on Oxy-FB combustion using Aspen Plus was also developed to predict combustion performance of any coal during Oxy-FB. It was observed that the concentrations of CO and SO2 were higher in the lower dense region of the bed. These levels, however, dropped significantly with the introduction of secondary oxygen. The simulation results were consistent with the experimental data. Overall, this thesis has identified several important issues, for the first time, on Oxy-FB combustion using brown coal. The information generated is useful for academics, industry and policy makers. Future research on Oxy-FB combustion can use the findings of this study while developing Oxy-FB combustion for brown coals

Oxy-fuel fluidized bed combustion of Victorian brown coal

Coal contributes to almost forty percent of global power generation. As conventional coal-fired power generation technologies result in large CO2 emission, the pursuit for new technologies focuses on either reducing CO2 emission or that allows easier capture of the emitted CO2 from coal-fired power plants. Oxy-fuel fluidized bed (Oxy-FB) combustion is one such technology due to its ability to produce concentrated CO2 stream in the flue gas. This concentrated CO2 allows easier capture for subsequent transportation and storage. Other important benefits of this technology are the potential for using any type of fuel, and the ability to control SO2 and NOX emissions. Despite its perceived advantages over conventional technologies, very little is known about the applicability of Oxy-FB for brown coal. Brown coal accounts for 91% of Victoria’s current electricity needs. Since Victoria has an estimated reserve of over 500 years of brown coal at the current consumption rate, successful application of Oxy-FB can potentially result in environment friendly power generation in Victoria. This first-ever study investigates the Oxy-FB combustion using Victorian brown coal in a combined experimental and modelling approach. The research involves designing and commissioning of a 10 kWth fluidized bed rig, carrying out experiments in laboratory scale and bench scale equipment, and performing thermodynamic and process modelling. Laboratory scale experiments using single char particle were conducted to investigate the combustion characteristics of individual and large char particle under Oxy-FB conditions. Particle temperature was observed to be higher compared to bed temperature. Up to 48°C difference was noticed between the char particle temperature and the bed temperature using 15% (v/v) steam in oxy-fuel combustion atmosphere. The temperature of the char particle during Oxy-FB combustion has practical implication for agglomeration. The bench scale experiments were carried out to evaluate combustion efficiency, agglomeration characteristics, sulphation characteristics, carbonation characteristics, NOX (NO, NO2 and N2O) emission, SOX (SO2 and SO3) emission, and trace elements (Hg, Se, As and Cr) emissions during Oxy-FB combustion of Victorian brown coal. A high level of CO2 concentration (90-94% in dry flue gas), over 99% combustion efficiency and no bed agglomeration under oxy-fuel combustion conditions including those with the addition of steam at temperatures between 800°C and 900°C. Moreover, the measured NOX and SOX concentration levels in the flue gas are within the permissible limits for coal-fired power plants in Victoria. This implies that additional NOX and SOX removal systems may not be required with Oxy-FB combustion of Victorian brown coal. The gaseous mercury concentrations, however, are considerably higher under oxy-fuel combustion compared to air combustion suggesting that mercury removal system may be required to avoid corrosion in the CO2 separation units if CO2 capture and transportation is intended. These conventional pollutants and trace elements emission characteristics are of great importance for the design of the gas cleaning systems for CO2 capture and storage (CCS) purposes. Furthermore, these results also provide information for selecting the optimum operating condition. Thermodynamic equilibrium modelling was carried out to predict the compounds formed during the combustion of Victorian brown coal under different Oxy-FB combustion conditions. It was predicted that the amount of toxic gaseous Cr6+ species was greater for oxy-fuel combustion than for air combustion. The distribution of toxic Se4+ species, however, remained almost the same in both combustion conditions within the typical temperature range for Oxy-FB combustion (800 - 950°C). A process model on Oxy-FB combustion using Aspen Plus was also developed to predict combustion performance of any coal during Oxy-FB. It was observed that the concentrations of CO and SO2 were higher in the lower dense region of the bed. These levels, however, dropped significantly with the introduction of secondary oxygen. The simulation results were consistent with the experimental data. Overall, this thesis has identified several important issues, for the first time, on Oxy-FB combustion using brown coal. The information generated is useful for academics, industry and policy makers. Future research on Oxy-FB combustion can use the findings of this study while developing Oxy-FB combustion for brown coals

Risk factors for perinatal stroke in term infants: A case-control study in Australia

Aim: The aetiology of perinatal stroke is poorly understood. This study aimed to prospectively confirm the risk factors and identify any previously unknown variables. Methods: A prospective case–control study was conducted in Australia. Univariate odds ratios (ORs), associated 95% confidence intervals (CIs) and multivariable logistic regression models fitted with backwards stepwise variable selection were used. Results: Sixty perinatal stroke cases reported between 2017 and 2019 included 95% (57/60) with multiple risk factors. Univariate analysis identified emergency caesarean section rather than NVD (P \u3c 0.01), low Apgar score (\u3c7) at 1, 5 and 10 min of age (P \u3e\u3c 0.01), resuscitation at birth (P \u3c 0.01), abnormal cord blood gas (P \u3c 0.01), neonatal infection/sepsis (P \u3c 0.01), congenital heart disease (P \u3c 0.01) and hypoglycaemia (P \u3c 0.01) as significant risk factors. Multivariate analysis found smoking during pregnancy (OR: 1.48; 95% CI: 1.09–1.99), 1-min Apgar score \u3c 7 (OR: 1.54; 95% CI: 1.15–2.08), 10-min Apgar score \u3c 7 (OR: 1.26; 95% CI: 1.02–1.54) and hypoglycaemia (OR: 1.49; 95% CI: 1.07–2.06). Conclusions: Perinatal stroke is associated with multiple risk factors. Exposure to smoking, 10-min Apgar score \u3c 7, neonatal infection and hypoglycaemia were independent risk factors. Emergency caesarean section, resuscitation at birth and abnormal cord blood gas were additional risk factors

Epidemiology and pathogenesis of stroke in preterm infants: A systematic review

Background: Perinatal stroke is one of the principal causes of cerebral palsy (CP) in preterm infants. Stroke in preterm infants is different from stroke in term infants, given the differences in brain maturation and the mechanisms of injury exclusive to the immature brain. We conducted a systematic review to explore the epidemiology and pathogenesis of periventricular hemorrhagic infarction (PVHI), perinatal arterial ischemic stroke (PAIS) and cerebral sinovenous thrombosis (CSVT) in preterm infants. Methods: Studies were identified based on predefined study criteria from MEDLINE, EMBASE, SCOPUS and WEB OF SCIENCE electronic databases from 2000 – 2019. Results were combined using descriptive statistics. Results: Fourteen studies encompassed 546 stroke cases in preterm infants between 23 – 36 weeks gestational ages and birth weights between 450 – 3500 grams. Eighty percent (436/546) of the stroke cases were PVHI, 17% (93/546) were PAIS and 3% (17/546) were CSVT. Parietal PVHI was more common than temporal and frontal lobe PVHI. For PAIS, left middle cerebral artery (MCA) was more common than right MCA or cerebellar stroke. For CSVT partial or complete thrombosis in the transverse sinus was universal. All cases included multiple possible risk factors, but the data were discordant precluding aggregation within a meta-analysis. Conclusion: This systematic review confirms paucity of data regarding the etiology and the precise causal pathway of stroke in preterm infants. Moreover, the preterm infants unlike the term infants do not typically present with seizures. Hence high index of clinical suspicion and routine cUS will assist in the timely diagnosis and understanding of stroke in this population