263 research outputs found

    The environmental constraints on cocoa (Theobroma cacao) production in north Australia

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    University of Technology, Sydney. Department of Environmental Science.This thesis describes the research undertaken to determine whether cocoa (Theobroma cacao) could be successfully produced in north Australia. Initial observations indicated that high solar radiation, high leaf-to-air vapour pressure differences (LAVPD) and cold over-night chilling temperatures would be the most significant environmental parameters affecting the performance of cocoa in north Australia. Experiments were carried out to assess the impact of supra-optimal and sub-optimal climatic conditions on cocoa performance using (1) cocoa seedlings established under solar irradiance ranging from 25 to 70% transmitted light; and (2) previously established cocoa to assess leaf photosynthetic performance, leaf chlorophyll fluorescence, leaf attributes, stem growth and yield quality and quantity under field conditions. Specific areas of study included: The effect of different shade treatments on cocoa establishment Cocoa seedlings subject to irradiance levels of 25 to 70% transmitted light showed no significant differences in relative growth rates. However, at 70% treatment canopies were smaller compared to the three lower light treatments. Differences in total canopy area were attributed to photoinhibition and results are discussed with reference to leaf carotenoid concentrations and leaf longevity. The effect of different shade treatments and environmental variables on leaf performance Maximum photosynthetic rates in the field ranged from approximately 1 to 9 μmol m⁻²s⁻ˡ. Differences in light saturated photosynthesis were attributed to differing shade treatments, changes in LAVPD (0.3 to 4.9 kPa), low and high leaf temperatures (8 to 42°C), dynamic photoinhibition (ΔF/Fm’ 0.2 to 0.7), leaf nitrogen content (1 .7 to 2.4%) and SLA (15 to 26 m² kg⁻ˡ). The impact of cold over-night temperatures Over-night chilling air temperatures of <10°C were shown to cause substantial reductions in the number of open photosystem II reaction centers (ΔF/Fm’) the following morning irrespective of shade treatment. Reductions in ΔF/ Fm’ were associated with extremely low rates of leaf carbon assimilation which was attributed to sub-optimal leaf thermodynamics and photosynthetic protein degradation. Recovery of photosynthesis took five days following chilling events in the field. Flowering response and bean quality under different light treatments Flowering was significantly reduced by 70% treatment during the first 25 months of growth. However, fruit yields were still the largest at 70% treatment compared to the three lower light treatments. This was thought to be an affect of larger canopy photosynthetic rates at 70% transmitted light. However, cocoa grown at 70% treatment produced smaller beans compared to the lower light treatments. Fat extracted from cocoa beans in the NT produced a softer butter than beans originating in Mossman, Queensland. Leaf gas exchange and growth between north Australian locations Experimental sites in north Queensland offered the most suitable growing conditions for cocoa. This was primarily attributed to low LAVPD throughout the year promoting large annual photosynthetic rates compared to cocoa grown in the Northern Territory and Western Australia

    Management and treatment outcomes of patients enrolled in MDR-TB treatment in Viet Nam.

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    SETTING: The programmatic management of drug-resistant tuberculosis (TB) in Viet Nam has been rapidly scaled up since 2009. OBJECTIVES: To document the annual numbers of patients enrolled for multidrug-resistant tuberculosis (MDR-TB) treatment during 2010-2014 and to determine characteristics and treatment outcomes of patients initiating treatment during 2010-2012. DESIGN: A retrospective cohort study using national reports and data from the national electronic data system for drug-resistant TB. RESULTS: The number of patients enrolled annually for MDR-TB treatment increased from 97 in 2010 to 1522 in 2014. The majority of patients were middle-aged men who had pulmonary disease and had failed a retreatment regimen; 77% had received ⩾2 courses of TB treatment. Favourable outcomes (cured and treatment completed) were attained in 73% of patients. Unfavourable outcomes included loss to follow-up (12.5%), death (8%) and failure (6.3%). Having had ⩾2 previous treatment courses and being human immunodeficiency virus-positive were associated with unfavourable outcomes. CONCLUSION: Increasing numbers of patients are being treated for MDR-TB each year with good treatment outcomes under national programme management in Viet Nam. However, there is a need to increase case detection-currently at 30% of the estimated 5100 MDR-TB cases per year, reduce adverse outcomes and improve monitoring and evaluation

    Modeling magnetic nanopolymer flow with induction and nanoparticle solid volume fraction effects : solar magnetic nanopolymer fabrication simulation

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    A mathematical model is presented for the nonlinear steady, forced convection, hydromagnetic flow of electro-conductive magnetic nano-polymer with magnetic induction effects included. The transformed two-parameter, non-dimensional governing partial differential equations for mass, momentum, magnetic induction and heat conservation are solved with the local non-similarity method (LNM) subject to appropriate boundary conditions. Keller’s implicit finite difference “box” method (KBM) is used to validate solutions. Computations for four different nanoparticles and three different base fluids are included. Silver nanoparticles in combination with various base fluids enhance temperatures and induced magnetic field and accelerate the flow. An elevation in magnetic body force number decelerates the flow whereas an increase in magnetic Prandtl number elevates the magnetic induction. Furthermore, increasing nanoparticle solid volume fraction is found to substantially boost temperatures. Applications of the study arise in advanced magnetic solar nano-materials (fluids) processing technologies

    Epidemiology and drug susceptibility of nontuberculous mycobacteria (NTM) in Italy in 2016-2020

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    Introduction. Nontuberculous mycobacteria (NTM) are environmental mycobacteria which may cause pulmonary and extrapulmonary diseases. These organisms are difficult to treat due to their intrinsic drug-resistance. In Italy, no major nationwide study on NTM epidemiology and drug susceptibility was performed.Methods. Data on the epidemiology of 7,469 NTM clinical isolates identified in Italy in 2016-2020 and on the minimum inhibitory concentrations (MICs) of 1,506 of these strains were analysed.Results. Overall, 63 species were identified in 42 hospital laboratories located in 16 out of 20 regions, with Mycobacterium avium complex (MAC) being the most frequently isolated, followed by M. gordonae, M. xenopi, M. abscessus. The MICs of 12 drugs for MAC, M. xenopi, M. kansasii, M. abscessus, M. fortuitum and M. chelonae were interpreted for clinical significance (susceptible, intermediate, resistant) based on the guidelines published by the Clinical and Laboratory Standards Institute in November 2018.Conclusions. Our data are in line with other nationwide studies and may be of value for further update of microbiological and clinical guidelines

    Early neonatal mortality and neurological outcomes of neonatal resuscitation in a resource-limited setting on the Thailand-Myanmar border: A descriptive study

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    Background Of the 4 million neonatal deaths worldwide yearly, 98% occur in low and middle-income countries. Effective resuscitation reduces mortality and morbidity but long-term outcomes in resource-limited settings are poorly described. This study reports on newborn neurological outcomes following resuscitation at birth in a resource-limited setting where intensive newborn care including intubation is unavailable. Methods Retrospective analysis of births records from 2008 to 2015 at Shoklo Malaria Research Unit (SMRU) on the Thailand-Myanmar border. Findings From 21,225 newbonrs delivered, 15,073 (71%) met the inclusion criteria (liveborn, singleton, ≥28 weeks’ gestation, delivered in SMRU). Neonatal resuscitation was performed in 460 (3%; 422 basic, 38 advanced) cases. Overall early neonatal mortality was 6.6 deaths per 1000 live births (95% CI 5.40–8.06). Newborns receiving basic and advanced resuscitation presented an adjusted rate for death of 1.30 (95%CI 0.66–2.55; p = 0.442), and 6.32 (95%CI 3.01–13.26; p<0.001) respectively, compared to newborns given routine care. Main factors related to increased need for resuscitation were breech delivery, meconium, and fetal distress (p<0.001). Neurodevelopmental follow-up to one year was performed in 1,608 (10.5%) of the 15,073 newborns; median neurodevelopmental scores of non-resuscitated newborns and those receiving basic resuscitation were similar (64 (n = 1565) versus 63 (n = 41); p = 0.732), while advanced resuscitation scores were significantly lower (56 (n = 5); p = 0.017). Interpretations Newborns requiring basic resuscitation at birth have normal neuro-developmental outcomes at one year of age compared to low-risk newborns. Identification of risk factors (e.g., breech delivery) associated with increased need for neonatal resuscitation may facilitate allocation of staff to high-risk deliveries. This work endorses the use of basic resuscitation in low-resource settings, and supports on-going staff training to maintain bag-and-mask ventilation skills

    Targeted Activation of Hippocampal Place Cells Drives Memory-Guided Spatial Behavior

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    The hippocampus is crucial for spatial navigation and episodic memory formation. Hippocampal place cells exhibit spatially selective activity within an environment and have been proposed to form the neural basis of a cognitive map of space that supports these mnemonic functions. However, the direct influence of place cell activity on spatial navigation behavior has not yet been demonstrated. Using an ‘all-optical’ combination of simultaneous two-photon calcium imaging and two-photon optogenetics, we identified and selectively activated place cells that encoded behaviorally relevant locations in a virtual reality environment. Targeted stimulation of a small number of place cells was sufficient to bias the behavior of animals during a spatial memory task, providing causal evidence that hippocampal place cells actively support spatial navigation and memory

    Confirmed archaeological evidence of water deer in Vietnam: relics of the Pleistocene or a shifting baseline?

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    Funder: Xuan Truong Construction EnterpriseStudies of archaeological and palaeontological bone assemblages increasingly show that the historical distributions of many mammal species are unrepresentative of their longer-term geographical ranges in the Quaternary. Consequently, the geographical and ecological scope of potential conservation efforts may be inappropriately narrow. Here, we consider a case-in-point, the water deer Hydropotes inermis, which has historical native distributions in eastern China and the Korean peninsula. We present morphological and metric criteria for the taxonomic diagnosis of mandibles and maxillary canine fragments from Hang Thung Binh 1 cave in Tràng An World Heritage Site, which confirm the prehistoric presence of water deer in Vietnam. Dated to between 13 000 and 16 000 years before the present, the specimens are further evidence of a wider Quaternary distribution for these Vulnerable cervids, are valuable additions to a sparse Pleistocene fossil record and confirm water deer as a component of the Upper Pleistocene fauna of northern Vietnam. Palaeoenvironmental proxies suggest that the Tràng An water deer occupied cooler, but not necessarily drier, conditions than today. We consider if the specimens represent extirpated Pleistocene populations or indicate a previously unrecognized, longer-standing southerly distribution with possible implications for the conservation of the species in the future

    Medial Entorhinal Cortex Selectively Supports Temporal Coding by Hippocampal Neurons

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    Recent studies have shown that hippocampal “time cells” code for sequential moments in temporally organized experiences. However, it is currently unknown whether these temporal firing patterns critically rely on upstream cortical input. Here we employ an optogenetic approach to explore the effect of large-scale inactivation of the medial entorhinal cortex on temporal, as well as spatial and object, coding by hippocampal CA1 neurons. Medial entorhinal inactivation produced a specific deficit in temporal coding in CA1 and resulted in significant impairment in memory across a temporal delay. In striking contrast, spatial and object coding remained intact. Further, we extended the scope of hippocampal phase precession to include object information relevant to memory and behavior. Overall, our work demonstrates that medial entorhinal activity plays an especially important role for CA1 in temporal coding and memory across time
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