2,539 research outputs found
Determination of wind tunnel constraint effects by a unified pressure signature method. Part 1: Applications to winged configurations
A new, fast, non-iterative version of the "Wall Pressure Signature Method" is described and used to determine blockage and angle-of-attack wind tunnel corrections for highly-powered jet-flap models. The correction method is complemented by the application of tangential blowing at the tunnel floor to suppress flow breakdown there, using feedback from measured floor pressures. This tangential blowing technique was substantiated by subsequent flow investigations using an LV. The basic tests on an unswept, knee-blown, jet flapped wing were supplemented to include the effects of slat-removal, sweep and the addition of unflapped tips. C sub mu values were varied from 0 to 10 free-air C sub l's in excess of 18 were measured in some cases. Application of the new methods yielded corrected data which agreed with corresponding large tunnel "free air" resuls to within the limits of experimental accuracy in almost all cases. A program listing is provided, with sample cases
Determination of wind tunnel constraint effects by a unified pressure signature method. Part 2: Application to jet-in-crossflow
The development of an improved jet-in-crossflow model for estimating wind tunnel blockage and angle-of-attack interference is described. Experiments showed that the simpler existing models fall seriously short of representing far-field flows properly. A new, vortex-source-doublet (VSD) model was therefore developed which employs curved trajectories and experimentally-based singularity strengths. The new model is consistent with existing and new experimental data and it predicts tunnel wall (i.e. far-field) pressures properly. It is implemented as a preprocessor to the wall-pressure-signature-based tunnel interference predictor. The supporting experiments and theoretical studies revealed some new results. Comparative flow field measurements with 1-inch "free-air" and 3-inch impinging jets showed that vortex penetration into the flow, in diameters, was almost unaltered until 'hard' impingement occurred. In modeling impinging cases, a 'plume redirection' term was introduced which is apparently absent in previous models. The effects of this term were found to be very significant
Keeping a lid on nodal : transcriptional and translational repression of nodal signalling
Nodal is an evolutionarily conserved member of the transforming growth factor-β (TGF-β) superfamily of secreted signalling factors. Nodal factors are known to play key roles in embryonic development and asymmetry in a variety of organisms ranging from hydra and sea urchins to fish, mice and humans. In addition to embryonic patterning, Nodal signalling is required for maintenance of human embryonic stem cell pluripotency and mis-regulated Nodal signalling has been found associated with tumour metastases. Therefore, precise and timely regulation of this pathway is essential. Here, we discuss recent evidence from sea urchins, frogs, fish, mice and humans that show a role for transcriptional and translational repression of Nodal signalling during early development
Detection and Phylogenetic Affiliation of Wolbachia Endosymbiont from Drosophila Melanogaster (India)
The cellular endosymbiont Wolbachia causes reproductive alterations in arthropod and nematode species. The presence of Wolbachia in natural populations of arthropods is made possible by their ability to manipulate the physiology of their host. This study evaluated the presence of Wolbachia in laboratory populations of Drosophila melanogaster (India). Using PCR based technology, WSP was amplified from D. melanogaster which yielded a 635bp gene. Here we report a different strain of Wolbachia which is placed in phylogenetic position along with the WMel Popcorn strain and Amergiers strain of India with Wolbachia A super group. Thus by comparing our results, the probable phenotype of the new strain of Wolbachia is identified. The information will be valuable in evolutionary studies of the endosymbiont Wolbachia and strain classification.
Abbreviations: WSP: Wolbachia Surface Protein PCR: Polymerase Chain Reaction MEGA: Molecular Evolutionary Genetics Analysi
Efficacy of intraarticular steroid injection in knee osteoarthritis using knee society score and visual analog score
Background: Osteoarthritis of knee is a chronic degenerative joint disease which leads to pain, swelling, stiffness and decreased quality of life. The purpose of this study was to assess the effect of intra-articular steroid injection for osteoarthritis knee by using knee society score (KSS) and visual analog scale (VAS).Methods: A prospective study of 38 patients (44 knees) diagnosed with osteoarthritis of knee were given 80mg of intra-articular methylprednisolone injection. The outcome was assessed using KSS and VAS before the injection and 3 months post injection.Results: The mean VAS improved 3 months post injection whereas there was no improvement in the mean KSS. The scores of VAS 3 months post injection were statistically significant whereas the KSS scores were statistically insignificant compared with the pre injection values.Conclusions: Intra-articular steroid injection for osteoarthritis of knee produces significant pain relief for most patients even in severe cases but this not translate to better functional outcomes
Overcoming catastrophic interference in connectionist networks using Gram-Schmidt orthogonalization.
Connectionist models of memory storage have been studied for many years, and aim to provide insight into potential mechanisms of memory storage by the brain. A problem faced by these systems is that as the number of items to be stored increases across a finite set of neurons/synapses, the cumulative changes in synaptic weight eventually lead to a sudden and dramatic loss of the stored information (catastrophic interference, CI) as the previous changes in synaptic weight are effectively lost. This effect does not occur in the brain, where information loss is gradual. Various attempts have been made to overcome the effects of CI, but these generally use schemes that impose restrictions on the system or its inputs rather than allowing the system to intrinsically cope with increasing storage demands. We show here that catastrophic interference occurs as a result of interference among patterns that lead to catastrophic effects when the number of patterns stored exceeds a critical limit. However, when Gram-Schmidt orthogonalization is combined with the Hebb-Hopfield model, the model attains the ability to eliminate CI. This approach differs from previous orthogonalisation schemes used in connectionist networks which essentially reflect sparse coding of the input. Here CI is avoided in a network of a fixed size without setting limits on the rate or number of patterns encoded, and without separating encoding and retrieval, thus offering the advantage of allowing associations between incoming and stored patterns. PACS Nos.: 87.10.+e, 87.18.Bb, 87.18.Sn, 87.19.La.The Royal Society; The Leverhulme Foundation (UK); National Initiative of Research in Cognitive Science by the Department of Science and Technology, Government of India.This is the final published version. It originally appeared in PLOS ONE at http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0105619
Privacy and Truthful Equilibrium Selection for Aggregative Games
We study a very general class of games --- multi-dimensional aggregative
games --- which in particular generalize both anonymous games and weighted
congestion games. For any such game that is also large, we solve the
equilibrium selection problem in a strong sense. In particular, we give an
efficient weak mediator: a mechanism which has only the power to listen to
reported types and provide non-binding suggested actions, such that (a) it is
an asymptotic Nash equilibrium for every player to truthfully report their type
to the mediator, and then follow its suggested action; and (b) that when
players do so, they end up coordinating on a particular asymptotic pure
strategy Nash equilibrium of the induced complete information game. In fact,
truthful reporting is an ex-post Nash equilibrium of the mediated game, so our
solution applies even in settings of incomplete information, and even when
player types are arbitrary or worst-case (i.e. not drawn from a common prior).
We achieve this by giving an efficient differentially private algorithm for
computing a Nash equilibrium in such games. The rates of convergence to
equilibrium in all of our results are inverse polynomial in the number of
players . We also apply our main results to a multi-dimensional market game.
Our results can be viewed as giving, for a rich class of games, a more robust
version of the Revelation Principle, in that we work with weaker informational
assumptions (no common prior), yet provide a stronger solution concept (ex-post
Nash versus Bayes Nash equilibrium). In comparison to previous work, our main
conceptual contribution is showing that weak mediators are a game theoretic
object that exist in a wide variety of games -- previously, they were only
known to exist in traffic routing games
Extending the DPSIR framework to analyse Driver-Pressure-State-Impact-Response of sand dune management in Manawatu-Whanganui (New Zealand) since the 19th century
Coastal sand dunes are multifunctional landscapes with rich biodiversity. In New Zealand, with the establishment of European settlement around 1840, dunes in the Manawatu-Whanganui region were affected due to the removal of their vegetation cover by human activities and animal grazing. As a result, sand drifted further inland affecting villages, infrastructure and agricultural areas. The main response was to introduce marram grass (Ammophila arenaria) used in Europe to stabilize dunes. This solution caused significant environmental impacts as marram grass turned invasive and native habitats of fauna and flora significantly decreased.This paper focused on the long-term analysis of aspects related to sand dune management in the region during two-time frames: 1) from the 19th to the late 20th century and 2) from then on to the early 21st century, using the innovative spiral DPSIR (Driver-Pressure-State-Impact-Response) framework. Data for this study comes from historical records, scientific literature and present management reports.The integrated spiral framework allows for establishing the connections between historical and future man-agement initiatives for mitigating and adapting to environmental impacts due to socio-economic drivers and their pressures. The study reinforces the paradigm shift from dune stabilization before the late 20th century to the restoration of stabilized dunes to make them active for enhancing native biodiversity should be again assessed in the context of sea-level rise during this century. Coastal managers should adopt an optimized solution between these two extreme solutions adopted from the 19th century to the present, by considering long-term and interdisciplinary analysis to better understand the systems' evolution and the full consequences of human actions.info:eu-repo/semantics/publishedVersio
A comparative study of phase evolution in YSZ powders, pellets and free-standing air plasma sprayed thermal barrier coatings
Please click Additional Files below to see the full abstract
- …