366 research outputs found
Superconducting Vortices and Elliptical Ferromagnetic Textures
In this article an analytical and numerical study of superconducting thin
film with ferromagnetic textures of elliptical geometries in close proximity is
presented. The screening currents induced in the superconductor due to the
magnetic texture are calculated. Close to the superconducting transition
temperature the spontaneous creation of superconducting vortices becomes
energy favorable depending on the value of the magnetization and the
geometrical quantities of the magnetic texture. The creation of vortices by
elliptic dots is more energy favorable than those created by circular ones. The
superconductor covered by elliptic dots array exhibits anisotropic transport
properties.Comment: 4 pages, 5figure
Formation of Two Component Bose Condensate During the Chemical Potential Curve Crossing
In this article we study the formation of the two modes Bose-Einstein
condensate and the correlation between them. We show that beyond the mean field
approximation the dissociation of a molecular condensate due to the chemical
potential curve crossing leads to the formation of two modes condensate. We
also show that these two modes are correlated in a two mode squeezed state.Comment: 10 page
Landspotting: Social gaming to collect vast amounts of data for satellite validation
At present there is no single satellite-derived global land cover product that is accurate enough to provide reliable estimates of forest or cropland area to determine, e.g., how much additional land is available to grow biofuels or to tackle problems of food security. The Landspotting Project aims to improve the quality of this land cover information by vastly increasing the amount of in-situ validation data available for calibration and validation of satellite-derived land cover. The Geo-Wiki (Geo-Wiki.org) system currently allows users to compare three satellite derived land cover products and validate them using Google Earth. However, there is presently no incentive for anyone to provide this data so the amount of validation through Geo-Wiki has been limited. However, recent competitions have proven that incentive driven campaigns can rapidly create large amounts of input. The LandSpotting Project is taking a truly innovative approach through the development of the Landspotting game. The game engages users whilst simultaneously collecting a large amount of in-situ land cover information. The development of the game is informed by the current raft of successful social gaming that is available on the internet and as mobile applications, many of which are geo-spatial in nature. Games that are integrated within a social networking site such as Facebook illustrate the power to reach and continually engage a large number of individuals. The number of active Facebook users is estimated to be greater than 400 million, where 100 million are accessing Facebook from mobile devices. The Landspotting Game has similar game mechanics as the famous strategy game "Civilization" (i.e. build, harvest, research, war, diplomacy, etc.). When a player wishes to make a settlement, they must first classify the land cover over the area they wish to settle. As the game is played on the earth surface with Google Maps, we are able to record and store this land cover/land use classification geographically. Every player can play the game for free (i.e. a massive multiplayer online game). Furthermore, it is a social game on Facebook (e.g. invite friends, send friends messages, purchase gifts, help friends, post messages onto the wall, etc). The game is played in a web browser, therefore it runs everywhere (where Flash is supported) without requiring the user to install anything additional. At the same time, the Geo-Wiki system will be modified to use the acquired in-situ validation information to create new outputs: a hybrid land cover map, which takes the best information from each individual product to create a single integrated version; a database of validation points that will be freely available to the land cover user community; and a facility that allows users to create a specific targeted validation area, which will then be provided to the crowdsourcing community for validation. These outputs will turn Geo-Wiki into a valuable system for earth system scientists
Game-Based Rehabilitation for Myoelectric Prosthesis Control
Background: A high number of upper extremity myoelectric prosthesis users abandon their devices due to difficulties in prosthesis control and lack of motivation to train in absence of a physiotherapist. Virtual training systems, in the form of video games, provide patients with an entertaining and intuitive method for improved muscle coordination and improved overall control. Complementary to established rehabilitation protocols, it is highly beneficial for this virtual training process to start even before receiving the final prosthesis, and to be continued at home for as long as needed.
Objective: The aim of this study is to evaluate (1) the short-term effects of a commercially available electromyographic (EMG) system on controllability after a simple video game-based rehabilitation protocol, and (2) different input methods, control mechanisms, and games.
Methods: Eleven able-bodied participants with no prior experience in EMG control took part in this study. Participants were asked to perform a surface EMG test evaluating their provisional maximum muscle contraction, fine accuracy and isolation of electrode activation, and endurance control over at least 300 seconds. These assessments were carried out (1) in a Pregaming session before interacting with three EMG-controlled computer games, (2) in a Postgaming session after playing the games, and (3) in a Follow-Up session two days after the gaming protocol to evaluate short-term retention rate. After each game, participants were given a user evaluation survey for the assessment of the games and their input mechanisms. Participants also received a questionnaire regarding their intrinsic motivation (Intrinsic Motivation Inventory) at the end of the last game.
Results: Results showed a significant improvement in fine accuracy electrode activation (P<.01), electrode separation (P=.02), and endurance control (P<.01) from Pregaming EMG assessments to the Follow-Up measurement. The deviation around the EMG goal value diminished and the opposing electrode was activated less frequently. Participants had the most fun playing the games when collecting items and facing challenging game play.
Conclusions: Most upper limb amputees use a 2-channel myoelectric prosthesis control. This study demonstrates that this control can be effectively trained by employing a video game-based rehabilitation protocol.(VLID)486422
Partial rupture of the quadriceps muscle in a child
<p>Abstract</p> <p>Background</p> <p>The quadriceps femoris muscle ruptures usually occur in the middle-aged population. We present a 4-year-old patient with partial rupture of the quadriceps femoris muscle. To our knowledge, this is the youngest patient reported with a quadriceps femoris muscle rupture.</p> <p>Case Presentation</p> <p>A 4-year-old girl admitted to our clinic with left knee pain and limitation in knee movements. Her father reported that she felt pain while jumping on sofa. There was no direct trauma to thigh or knee. We located a palpable soft tissue swelling at distal anterolateral side of thigh. The history revealed that 10 days ago the patient was treated for upper tract respiratory infection with intramuscular Clindamycin for 7 days. When we consulted the patient with her previous doctor and nurse, we learnt that multiple daily injections might be injected to same side of left thigh. MRI showed a partial tear of vastus lateralis muscle matching with the injection sites. The patient treated with long leg half-casting for three weeks. Clinical examination and knee flexion had good results with conservative treatment.</p> <p>Conclusions</p> <p>Multiple intramuscular injections may contribute to damage muscles and make prone to tears with muscle contractions. Doctors and nurses must be cautious to inject from different parts of both thighs.</p
Kinking of Frozen Elephant Trunk Hybrid Prostheses: Incidence, Mechanism, and Management
Introduction:
Kinking of the Frozen Elephant Trunk (FET) stent graft is one of the most devastating complications of the FET procedure. It can present post-operatively with reduced arterial pressures in the lower limbs and intermittent claudication. However, it can also be visualized intra-operatively by the surgeons. Unresolved kinking of the stent graft can result in intraluminal thrombus formation and subsequent multi-organ septic emboli.
Aims:
The main scope of this review is to collate, summarize and present all the evidence in the literature on kinking of FET stent grafts.
Methods:
We carried out a comprehensive literature search on multiple electronic databases including PubMed, EMBASE, Ovid, and Scopus to collate all research evidence on the incidence, mechanism, and management of FET graft kinking.
Results:
Incidence of kinking is variable, ranging from 0% to 8% in the literature, with varying rates associated with each stent graft type. The Thoraflex HybridTM prosthesis seemed to be the most commonly used and superior graft, and out of all the 15 cases of kinking reported in the literature, 5 (33.3%) were associated with just the Frozenix graft which had the highest incidence. There are multiple theories regarding the mechanism of kinking, including the direction of blood flow, the length of the stent grafts used, and the position of the prosthesis in relation to the flexure of the aorta. Multiple reparative management techniques have been suggested in the literature and include total endovascular repair, open repair, balloon dilatation, and deploying a second stent graft.
Conclusion:
Graft kinking is one of the most critical complications of the FET technique. Its life-threatening sequelae warrant appropriate follow-up of these patients post-operatively, in addition to time management if kinking is suspected. Given the limited evidence in the literature, future studies should incorporate graft kinking into their outcomes reporting
Magnetic Pinning of Vortices in a Superconducting Film: The (anti)vortex-magnetic dipole interaction energy in the London approximation
The interaction between a superconducting vortex or antivortex in a
superconducting film and a magnetic dipole with in- or out-of-plane
magnetization is investigated within the London approximation. The dependence
of the interaction energy on the dipole-vortex distance and the film thickness
is studied and analytical results are obtained in limiting cases. We show how
the short range interaction with the magnetic dipole makes the co-existence of
vortices and antivortices possible. Different configurations with vortices and
antivortices are investigated.Comment: 12 pages, 12 figures. Submitted to Phys. Rev.
Field Research Is Essential to Counter Virological Threats
The interface between humans and wildlife is changing and, with it, the potential for pathogen introduction into humans has increased. Avian influenza is a prominent example, with an ongoing outbreak showing the unprecedented expansion of both geographic and host ranges. Research in the field is essential to understand this and other zoonotic threats. Only by monitoring dynamic viral populations and defining their biology in situ can we gather the information needed to ensure effective pandemic preparation.</p
The feasibility of canine rabies elimination in Africa: dispelling doubts with data
<p><b>Background:</b> Canine rabies causes many thousands of human deaths every year in Africa, and continues to increase throughout much of the continent.</p>
<p><b>Methodology/Principal Findings:</b> This paper identifies four common reasons given for the lack of effective canine rabies control in Africa: (a) a low priority given for disease control as a result of lack of awareness of the rabies burden; (b) epidemiological constraints such as uncertainties about the required levels of vaccination coverage and the possibility of sustained cycles of infection in wildlife; (c) operational constraints including accessibility of dogs for vaccination and insufficient knowledge of dog population sizes for planning of vaccination campaigns; and (d) limited resources for implementation of rabies surveillance and control. We address each of these issues in turn, presenting data from field studies and modelling approaches used in Tanzania, including burden of disease evaluations, detailed epidemiological studies, operational data from vaccination campaigns in different demographic and ecological settings, and economic analyses of the cost-effectiveness of dog vaccination for human rabies prevention.</p>
<p><b>Conclusions/Significance:</b> We conclude that there are no insurmountable problems to canine rabies control in most of Africa; that elimination of canine rabies is epidemiologically and practically feasible through mass vaccination of domestic dogs; and that domestic dog vaccination provides a cost-effective approach to the prevention and elimination of human rabies deaths.</p>
A single residue substitution in the receptor-binding domain of H5N1 hemagglutinin is critical for packaging into pseudotyped lentiviral particles
© 2012 Tang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Serological studies for influenza infection and vaccine response often involve microneutralization and hemagglutination inhibition assays to evaluate neutralizing antibodies against human and avian influenza viruses, including H5N1. We have previously characterized lentiviral particles pseudotyped with H5-HA (H5pp) and validated an H5pp-based assay as a safe alternative for high-throughput serological studies in BSL-2 facilities. Here we show that H5-HAs from different clades do not always give rise to efficient production of H5pp and the underlying mechanisms are addressed.
Methodology/Findings: We have carried out mutational analysis to delineate the molecular determinants responsible for efficient packaging of HA from A/Cambodia/40808/2005 (H5Cam) and A/Anhui/1/2005 (H5Anh) into H5pp. Our results demonstrate that a single A134V mutation in the 130-loop of the receptor binding domain is sufficient to render H5Anh the ability to generate H5Anh-pp efficiently, whereas the reverse V134A mutation greatly hampers production of H5Cam-pp. Although protein expression in total cell lysates is similar for H5Anh and H5Cam, cell surface expression of H5Cam is detected at a significantly higher level than that of H5Anh. We further demonstrate by several independent lines of evidence that the behaviour of H5Anh can be explained by a stronger binding to sialic acid receptors implicating residue 134.
Conclusions: We have identified a single A134V mutation as the molecular determinant in H5-HA for efficient incorporation into H5pp envelope and delineated the underlying mechanism. The reduced binding to sialic acid receptors as a result of the A134V mutation not only exerts a critical influence in pseudotyping efficiency of H5-HA, but has also an impact at the whole virus level. Because A134V substitution has been reported as a naturally occurring mutation in human host, our results may have implications for the understanding of human host adaptation of avian influenza H5N1 virusesThis work was supported by grants from the Research Fund for the Control of Infectious Diseases of Hong Kong (RFCID#08070972), the Area of
Excellence Scheme of the University Grants Committee (grant AoE/M-12/-06 of the Hong Kong Special Administrative Region, China), the French Ministry of Health, and the RESPARI project of the Institut Pasteur International Network
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