459 research outputs found
Microbial ecology of Rum Jungle II: environmental study of two flooded opencuts and smaller, associated water bodies.
The microbial status of the flooded Intermediate and White's opencuts of the abandoned uranium mine at Rum Jungle was investigated by sampling the water column and sediments of several areas in each opencut. Smaller water bodies associated with the experimental heap-leach pile were also investigated. Several groups of bacteria were identified and population sizes were estimated using selective media techniques. Various physicochemical parameters of each sample were determined and correlated with the occurence of bacteria. Both opencuts although behaving differently were found to be heavily polluted by sulphuric acid and heavy metals White's more so than Intermediate. White's opencut was found to be stratified into an aerobic zone about five metres deep and a microaerophilic zone below this. Large populations of Thiobacillus ferrooxidans and autotrophic sulphur-oxidising bacteria indicated that degradation of sulphidic minerals in the walls and floors of the opencuts was still occurring. The isolation of T. ferrooxidans from sediments also containing anaerobic bacterial species suggested that T. ferrooxidans was degrading sulphidic minerals either anaerobically or microaerophilically. The smaller water bodies also were found to be heavily polluted by acid and heavy metals from drainage and seepage from the sulphidic heap-leach pile
Microbial ecology of Rum Jungle III : leaching behaviour of sulphidic waste material under controlled conditions.
The discharge into river systems of acid and heavy metals generated by leaching of sulphidic waste materials at the abandoned opencut uranium mine at Rum Jungle Northern Territory is causing continuing pollution of the surrounding environment. The maximum effects of acid and microorganisms on samples from the overburden dump material under defined and controlled environmental conditions were assessed using reactor systems. These samples came from the overburden dump resulting from the mining of White's orebody. Similarly the stability of tailings material under conditions of flooding and increasing acidity was determined. At ph 2.5 metals in White's dump material were solubilised by acid attack only whereas at pH 3.5 bacterial activity (principally that of Thiobacillus ferrooxidans) generated acidity and contributed significantly to metal release. Under microaerophilic conditions Thiobacillus ferrooxidans continued to effect metal release from the ore but did not produce further acidity. If White's overburden is returned to the acidic flooded opencuts complete solubilisation of the material will occur. The exclusion of oxygen from the dump will not necessarily stop bacterially catalysed leaching processes. Under highly aerated and agitated flooded conditions the tailings material was not active except for copper release of about 2 g kg -1 ore at pH 4.0. The only deleterious element released by increasing acidity was copper which was 100 per cent solubilised at pH 2.5. Uranium was always lss than 3 mu g kg -1 ore and lead was detected only at pH 2.5. Indigenous leaching bacteria did not develop
Quantum teleportation on a photonic chip
Quantum teleportation is a fundamental concept in quantum physics which now
finds important applications at the heart of quantum technology including
quantum relays, quantum repeaters and linear optics quantum computing (LOQC).
Photonic implementations have largely focussed on achieving long distance
teleportation due to its suitability for decoherence-free communication.
Teleportation also plays a vital role in the scalability of photonic quantum
computing, for which large linear optical networks will likely require an
integrated architecture. Here we report the first demonstration of quantum
teleportation in which all key parts - entanglement preparation, Bell-state
analysis and quantum state tomography - are performed on a reconfigurable
integrated photonic chip. We also show that a novel element-wise
characterisation method is critical to mitigate component errors, a key
technique which will become increasingly important as integrated circuits reach
higher complexities necessary for quantum enhanced operation.Comment: Originally submitted version - refer to online journal for accepted
manuscript; Nature Photonics (2014
The exposure of the Great Barrier Reef to ocean acidification
© 2016, Nature Publishing Group. All rights reserved. The Great Barrier Reef (GBR) is founded on reef-building corals. Corals build their exoskeleton with aragonite, but ocean acidification is lowering the aragonite saturation state of seawater (Ωa). The downscaling of ocean acidification projections from global to GBR scales requires the set of regional drivers controlling Ωa to be resolved. Here we use a regional coupled circulation-biogeochemical model and observations to estimate the Ωa experienced by the 3,581 reefs of the GBR, and to apportion the contributions of the hydrological cycle, regional hydrodynamics and metabolism on Ωa variability. We find more detail, and a greater range (1.43), than previously compiled coarse maps of Ωa of the region (0.4), or in observations (1.0). Most of the variability in Ωa is due to processes upstream of the reef in question. As a result, future decline in Ωa is likely to be steeper on the GBR than currently projected by the IPCC assessment report
A novel technique for the treatment of post operative retro-rectal haematoma: two case reports
Rectal bleeding following any form of rectal surgery is a well recognised complication 1, 2, 3 & 4. However retro-rectal bleeding and tracking which then presents as rectal bleeding has not been reported in the literature. We describe a novel way of dealing with this technically difficult post-operative complication
Integrated photonic quantum gates for polarization qubits
Integrated photonic circuits have a strong potential to perform quantum
information processing. Indeed, the ability to manipulate quantum states of
light by integrated devices may open new perspectives both for fundamental
tests of quantum mechanics and for novel technological applications. However,
the technology for handling polarization encoded qubits, the most commonly
adopted approach, is still missing in quantum optical circuits. Here we
demonstrate the first integrated photonic Controlled-NOT (CNOT) gate for
polarization encoded qubits. This result has been enabled by the integration,
based on femtosecond laser waveguide writing, of partially polarizing beam
splitters on a glass chip. We characterize the logical truth table of the
quantum gate demonstrating its high fidelity to the expected one. In addition,
we show the ability of this gate to transform separable states into entangled
ones and vice versa. Finally, the full accessibility of our device is exploited
to carry out a complete characterization of the CNOT gate through a quantum
process tomography.Comment: 6 pages, 4 figure
The Epidemiology and Clinical Spectrum of Melioidosis: 540 Cases from the 20 Year Darwin Prospective Study
Melioidosis is an occupationally and recreationally acquired infection important in Southeast Asia and northern Australia. Recently cases have been reported from more diverse locations globally. The responsible bacterium, Burkholderia pseudomallei, is considered a potential biothreat agent. Risk factors predisposing to melioidosis are well recognised, most notably diabetes. The Darwin prospective melioidosis study has identified 540 cases of melioidosis over 20 years and analysis of the epidemiology and clinical findings provides important new insights into this disease. Risk factors identified in addition to diabetes, hazardous alcohol use and chronic renal disease include chronic lung disease, malignancies, rheumatic heart disease, cardiac failure and age ≥50 years. Half of patients presented with pneumonia and septic shock was common (21%). The decrease in mortality from 30% in the first 5 years of the study to 9% in the last five years is attributed to earlier diagnosis and improvements in intensive care management. Of the 77 fatal cases (14%), all had known risk factors for melioidosis. This supports the most important conclusion of the study, which is that melioidosis is very unlikely to kill a healthy person, provided the infection is diagnosed early and resources are available to provide appropriate antibiotics and critical care where required
Higher media multi-tasking activity is associated with smaller gray-matter density in the anterior cingulate cortex
Media multitasking, or the concurrent consumption of multiple media forms, is increasingly prevalent in today’s society and has been associated with negative psychosocial and cognitive impacts. Individuals who engage in heavier media-multitasking are found to perform worse on cognitive control tasks and exhibit more socio-emotional difficulties. However, the neural processes associated with media multi-tasking remain unexplored. The present study investigated relationships between media multitasking activity and brain structure. Research has demonstrated that brain structure can be altered upon prolonged exposure to novel environments and experience. Thus, we expected differential engagements in media multitasking to correlate with brain structure variability. This was confirmed via Voxel-Based Morphometry (VBM) analyses: Individuals with higher Media Multitasking Index (MMI) scores had smaller gray matter density in the anterior cingulate cortex (ACC). Functional connectivity between this ACC region and the precuneus was negatively associated with MMI. Our findings suggest a possible structural correlate for the observed decreased cognitive control performance and socio-emotional regulation in heavy media-multitaskers. While the cross-sectional nature of our study does not allow us to specify the direction of causality, our results brought to light novel associations between individual media multitasking behaviors and ACC structure differences
Cone-rod dystrophy can be a manifestation of Danon disease
Background Danon disease is a neuromuscular disorder with variable expression in the eye. We describe a family with Danon disease and cone-rod dystrophy (CRD). Methods Affected males of one family with Danon were invited for an extensive ophthalmologic examination, including color vision testing, fundus photography, Goldmann perimetry, full-field electroretinogram (ERG), and SD-OCT. Previous ophthalmologic data were retrieved from medical charts. The LAMP2 and RPGR gene were analyzed by direct sequencing. Results Two siblings had no ocular phenotype. The third sibling and a cousin developed CRD leading to legal blindness. Visual acuity deteriorated progressively over time, color vision was severely disturbed, and ERG showed reduced photopic and scotopic responses. SD-OCT revealed thinning of the photoreceptor and RPE layer. Visual fieldsdemonstrated central scotoma. The causal mutation was p. Gly384Arg in LAMP2; no mutations were found in RPGR. Conclusions This is the first description of CRD in Danon disease. The retinal phenotype was a late onset but severe dystrophy characterized by loss of photoreceptors and RPE cells. With this report, we highlight the importance of a comprehensive ophthalmologic examination in the clinical work-up of Danon disease
Automated Analysis of Cryptococcal Macrophage Parasitism Using GFP-Tagged Cryptococci
The human fungal pathogens Cryptococcus neoformans and C. gattii cause life-threatening infections of the central nervous system. One of the major characteristics of cryptococcal disease is the ability of the pathogen to parasitise upon phagocytic immune effector cells, a phenomenon that correlates strongly with virulence in rodent models of infection. Despite the importance of phagocyte/Cryptococcus interactions to disease progression, current methods for assaying virulence in the acrophage system are both time consuming and low throughput. Here, we introduce the first stable and fully characterised GFP–expressing derivatives of two widely used cryptococcal strains: C. neoformans serotype A type strain H99 and C. gattii serotype B type strain R265. Both strains show unaltered responses to environmental and host stress conditions and no deficiency in virulence in the macrophage model system. In addition, we report the development of a method to effectively and rapidly investigate macrophage parasitism by flow cytometry, a technique that preserves the accuracy of current approaches but offers a four-fold improvement in speed
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