1,179 research outputs found
Morphology of Tigris River within Baghdad City
In recent years, substantial changes have occurred in the morphology of the River Tigris within Baghdad City. Although huge volumes of sediment are being trapped in recently constructed headwater reservoirs, the number of islands in the Tigris at Baghdad is increasing. The debris of bridges destroyed in the wars of 1991 and 2003 and their subsequent reconstruction have enhanced the development of these islands. As a consequence the ability of the river to carry the peaks of flood waters has been reduced. This has led to potential increase of flooding in parts of the city. <br><br> The bed of the River Tigris has been surveyed on three occasions (1976, 1991, and 2008). The most recent survey was conducted by the Ministry of Water Resources, extended 49 km from the Al-Muthana Bridge north Baghdad to the confluence with the Diyala River south Baghdad. It yielded cross-section profiles at 250 m intervals. The data are used to predict the maximum flood capacity for the river using the one-dimensional hydraulic model for steady flow "HEC-RAS" modeling. Calibration of the model was carried out using field measurements for water levels along the last 15 km of the reach and the last 10 yr of observation at the Sarai Baghdad gauging station. <br><br> The model showed a significant predicted reduction in the current river capacity below that which the river had carried during the floods of 1971 and 1988. The three surveys conducted on the same reach of the Tigris indicated that the ability of the river to transport water has decreased
Development of a life cycle assessment tool for the assessment of food production systems within the energy, water and food nexus
© 2015 The Institution of Chemical Engineers.As the demand for services and products continues to increase in light of rapid population growth, the question of energy, water and food (EWF) security is of increasing importance. The systems representing the three resources are intrinsically connected and, as such, there is a need to develop assessment tools that consider their interdependences. Specifically when evaluating the environmental performance of a food production system, it is necessary to understand its life cycle. The objective of this paper is to introduce an integrated energy, water and food life cycle assessment tool that integrates EWF resources in one robust model and at an appropriate resolution. The nexus modelling tool developed is capable of providing an environmental assessment for food production systems utilising a holistic systems approach as described by a series of subsystems that constitute each of the EWF resources. A case study set in Qatar and characterised by an agriculture sub-system, which includes the production and application of fertilisers and the raising of livestock, a water sub-system represented by mechanical and thermal desalination processes and an energy sub-system, which includes fossil fuel in the form of combined cycle natural gas based energy production and solar renewable energy is used to illustrate the model function. For the nexus system analysed it is demonstrated that the food system is the largest contributor to global warming. The GWP can be reduced by up to 30% through the utilisation of solar energy to substitute fossil fuels, which, however, comes with a significant requirement for land investment
Cluster headache: an overview of established and emerging treatments
Cluster headache is a rare but disabling neurological disorder, characterised, according to the International Classification of Headache Disorders-3 (ICHD-3), by unilateral severe headache with associated autonomic features and agitation. Despite proven abortive and preventive treatments, many cases remain refractory, leading to adverse psychosocial and employment outcomes. Understanding the efficacy of current and emerging therapies may help to improve clinical management of such cases.
This month’s journal club reviews three papers relating to treatment of cluster headache. The first explores the effectiveness and adverse effects of a range of acute treatments for cluster headache, based on a large international sample. The second is a pooled analysis of two previous trials evaluating non-invasive vagus nerve stimulation (nVNS) as an acute treatment for cluster headache. The third paper describes a double-blind, randomised, placebo-controlled study assessing the monoclonal antibody galcanezumab as a preventive agent for cluster headache
Postural orthostatic tachycardia syndrome: insights into pathogenesis and treatment
Postural orthostatic tachycardia syndrome (POTS) is a form of chronic dysautonomia, most commonly seen in women of child-bearing age and often associated with reduced quality of life. Current diagnostic criteria require an increase in heart rate of 30 beats per minute (bpm), or over 120 bpm in the first 10 min of standing, in the absence of orthostatic hypotension, and associated with orthostatic intolerance. Other symptoms suggestive of autoimmune failure include sudomotor dysfunction and gastrointestinal dysmotility. However, the heterogeneity of clinical presentation and uncertainty of pathogenesis, often prompts a search for alternative causes before a diagnosis of POTS, a made
Constrained Statistical Modelling of Knee Flexion from Multi-Pose Magnetic Resonance Imaging
© 1982-2012 IEEE.Reconstruction of the anterior cruciate ligament (ACL) through arthroscopy is one of the most common procedures in orthopaedics. It requires accurate alignment and drilling of the tibial and femoral tunnels through which the ligament graft is attached. Although commercial computer-Assisted navigation systems exist to guide the placement of these tunnels, most of them are limited to a fixed pose without due consideration of dynamic factors involved in different knee flexion angles. This paper presents a new model for intraoperative guidance of arthroscopic ACL reconstruction with reduced error particularly in the ligament attachment area. The method uses 3D preoperative data at different flexion angles to build a subject-specific statistical model of knee pose. To circumvent the problem of limited training samples and ensure physically meaningful pose instantiation, homogeneous transformations between different poses and local-deformation finite element modelling are used to enlarge the training set. Subsequently, an anatomical geodesic flexion analysis is performed to extract the subject-specific flexion characteristics. The advantages of the method were also tested by detailed comparison to standard Principal Component Analysis (PCA), nonlinear PCA without training set enlargement, and other state-of-The-Art articulated joint modelling methods. The method yielded sub-millimetre accuracy, demonstrating its potential clinical value
Assessment of the Effect of two Different Digital Fabrication Techniques on Marginal and Internal Fit of Interim Fixed Dental Prothesis
Aim: The aim of that study was to evaluate the marginal and internal fit of a 3-unit, and 6-unit interim fixed dental prosthesis manufactured through milling and 3D printing technologies. Materials and Methods: Forty-eight interim fixed dental prostheses (FDP) were equally divided into two groups according to the fabrication technique. In group (MT), specimens were fabricated through milling technology while in group (PT), specimens were obtained by 3D printing. Each group was subdivided equally according to the FDP span length into 3-unit FDP (SFDP), and 6-unit FDP (LFDP). Marginal and internal fit were measured through the superimposition of the digital master model data and data of the fitting surfaces of the milled and printed FDPs using the “best-fit” alignment feature of a 3D evaluation superimposition software. The Mann-Whitney U test was used to compare the two fabrication techniques as well as the two span lengths. The significance level was set at P \u3c 0.05. Results: Results showed that 3D printing showed statistically significantly higher overall marginal gap distance (MGD) than the milling technique for the (SFDP) subgroup while milling showed higher overall (MGD) values than 3D printing for the (LFDP) subgroup. For internal fit, 3D printing showed lower overall internal gap distance values than milling. Conclusions: Milling technology was able to produce restorations with better marginal fit compared to 3D printing only in 3-unit FDPs. However, the opposite was true when the internal fit of the restorations was considered where 3D printing surpassed the milling technique in both the short-span and long-span FDPs. Consequently, 3D printing could be the technique of preference for fabricating provisional restorations especially when it comes to complex long span FDPs
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