784 research outputs found

    Endoscopic repair of cerebrospinal fluid leaks

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    Developmental Venous Anomalies are a normal variant that may be associated with other cerebral vascular malformation they have bean previously referred to Venous angiomas. DVAs are the most frequently encountered cerebral vascular malformation and their incidence is reported to be high as 2.6%. DVAs are classified into two types based on draining veins. Either deep or superficial. Those that drain into subependymal veins are classified as deep and those that drain into cortical pial veins are classified as superficial. The trans-cerebral veins join either the deep or superficial venous systems by crossing a varying length of the brain parenchyma. Controversy surrounds their exact clinical significance, as DVAs are rarely symptomatic. The symptoms displayed by a patient can be related to a lesion that is associated with DVAs, such as a cavernoma. Study Aim: To describe the patients presenting to a single unit over a 10-year period with symptoms attributable to a DVA. Results: Out of 19 patients in the database with the diagnosis of DVA, 10 were identified where the clinical presentation was directly related to the DVA. Seven of the patients presented with haemorrhage, 6 had parenchymal bleeds and one was intraventricular. Two patients had neurological deficit, 1 was transient and one was progressive. One patient had sudden severe headache with no evidence of haemorrhage on CT scan. The age range was from 14 to 55 with a mean of 32,7 years. Four patients were male and 6 were female. Of the patients that presented with haemorrhage only one had a fistula, three other patients with haemorrhage had evidence on DSA of stenosis of the large collector vein, In the remaining 3 patients no reason for the bleed could be detected. One patient presented with left hemianopia that resolved after several hours, DSA showed minimal caput medusa with delayed filling of the collector vein. The other patient that presented with progressive neurological deficit in the form of progressive leg spasticity and dysarthria, Angiography showed a large collecting vein that drains in the jugular bulb was stenosed. The last patient that presented with sudden sever headaches, with no haemorrhage identified on CT scan, On DSA there was early filling of the DVA veins compared to other cerebral veins and two prominent posterior communicating thalamoperforating vessels were seen. Conclusion: Developmental venous anomalies are the commonest vascular malformation, and are rarely symptomatic unless associated with a cavernoma. In patients that have symptoms linked to DVAs (Haemorrhage, neurological deficit, sudden sever headaches) overall they have a good outcome, and the deficit related to a DVA tend to improve overtime, except for one patient that we had in our group, the DVA draining the pons and the cerebellar hemisphere had a tight outflow stenosis, that lead to progressive neurological deficit. In general, the majority of DVAs that are symptomatic do well

    First look analyses of five cycles of ERTS-1 imagery over County of Los Angeles: Assessment of data utility for urban development and regional planning

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    Significant results have been obtained from the analyses of ERTS-1 imagery from five cycles over Test Site SR 124 by classical photointerpretation and by an interactive hybrid multispectral information extraction system (GEMS). The synopticity, periodicity and multispectrality of ERTS coverage, available for the first time to LA County planners, have opened up both a new dimensionality in data and offer new capability in preparation of planning inputs. Photointerpretation of ERTS images has produced over 25 overlays at 1:1,000,000 scale depicting regional relations and urban structure in terms of several hundred linear and areal features. To mention only one such result, a possible new fault lineament has been discovered on the northern slope of the Santa Monica mountains in the scene 1144-18015, composited of MSS bands 4, 5, 6,. GEMS analysis of the ERTS products has provided new or improved information in the following planning data categories: urban vegetation; land cover segregation; man-made and natural impact monitoring; urban design; and suitability. ERTS data analysis has allowed planners to establish trends that directly impact planning policies. This new source of information will not only assist current methods to be more efficient, but permits entirely new planning methodologies to be employed

    Myringoplasty - effects on hearing and contributing factors

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    Indications for myringoplasty are chronic otorrhoea and hearing impairment. Some authors have described poor postoperative hearing results and sensorineural hearing loss associated with the surgery, and question the indication for myringoplasty on an ear with normal hearing « 25 dB). This study of 211 Consecutive myringoplasties performed over 1 year details the 'take rate,' hearing gains and losses, and factors found to influence the above. The take rate of 78% is comparable with figures in the literature. The most significant factors influencing this are the grade of the surgeon and the size of the perforation. The average pre-operative air-bone gap was closed from 23,7 dB to 13,9 dB with a 4,5% incidence of postoperative sensorineural hearing loss. Postoperatively 77,9% of patients had an air-bone gap of less than 20 dB. We conclude that myringoplasty is a beneficial procedure, closing the tympanic membrane and improving the hearing

    Transmitter Optimization in Multiuser Wireless Systems with Quality of Service Constraints

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    In this dissertation, transmitter adaptation for optimal resource allocation in wireless communication systems are investigated. First, a multiple access channel model is considered where many transmitters communicate with a single receiver. This scenario is a basic component of a. wireless network in which multiple users simultaneously access the resources of a wireless service provider. Adaptive algorithms for transmitter optimization to meet Quality-of-Service (QoS) requirements in a distributed manner are studied. Second, an interference channel model is considered where multiple interfering transmitter-receiver pairs co-exist such that a given transmitter communicates with its intended receiver in the presence of interference from other transmitters. This scenario models a wireless network in which several wireless service providers share the spectrum to offer their services by using dynamic spectrum access and cognitive radio (CR) technologies. The primary objective of dynamic spectrum access in the CR approach is to enable use of the frequency band dynamically and opportunistically without creating harmful interference to licensed incumbent users. Specifically, CR users are envisioned to be able to provide high bandwidth and efficient utilization of the spectrum via dynamic spectrum access in heterogeneous networks. In this scenario, a distributed method is investigated for combined precoder and power adaptation of CR transmitters for dynamic spectrum sharing in cognitive radio systems. Finally, the effect of limited feedback for transmitter optimization is analyzed where precoder adaptation uses the quantized version of interference information or the predictive vector quantization for incremental updates. The performance of the transmitter adaptation algorithms is also studied in the context of fading channels

    Surgical challenge: endoscopic repair of cerebrospinal fluid leak

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    BACKGROUND: Cerebrospinal fluid leaks (CSF) result from an abnormal communication between the subarachnoid space and the extracranial space. Approximately 90% of CSF leak at the anterior skull base manifests as rhinorrhea and can become life-threatening condition. Endoscopic sinus surgery (ESS) has become a common otolaryngologist procedure. The aim of this article is to consider our experience and to evaluate the outcomes in patients who underwent a purely endoscopic repair of CSF leaks of the anterior skull base. FINDINGS: Retrospective chart review was performed of all patients surgically treated for CSF leaks presenting to the Section of Nasal and Sinus Disorders at the Service of ENT–Head and Neck Surgery, University Hospital Complex of Santiago de Compostela (CHUS), between 2004 and 2010. A total of 30 patients who underwent repair CSF leak by ESS. The success rate was 93.4% at the first attempt; only two patients (6.6%) required a second surgical procedure, and none of it was necessary to use a craniotomy for closure. Follow-up periods ranged from 4 months to 6 years. CONCLUSION: Identifying the size, site, and etiology of the CSF leak remains the most important factor in the surgical success. It is generally accepted that the ESS have made procedures minimally invasive, and CSF leak is now one of its well-established indications with low morbidity and high success rate, with one restriction for fistulas of the posterior wall of the frontal sinus should be repaired in conjunction with open techniques

    Cavity Disinfection With a 445 nm Diode Laser Within the Scope of Restorative Therapy – A Pilot Study

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    Introduction: Cavity disinfection is necessary to prevent a progressive infection of the crown dentin and pulp. Increasing intolerance and resistance to antiseptics and antibiotics as well as the controversy over the effects of those on the dental hard tissue and composite have prompted the investigation of alternative treatment options. The objective of this pilot study is to evaluate the antibacterial potential of a diode laser with a wavelength of 445 nm in the cavity preparation using the bacterium Streptococcus salivarius associated with caries in conjunction with the characteristics and influences of dentin on light transmission.Methods: The bactericidal effect of the laser irradiation was determined in culture experiments by using caries-free human dentin samples on bacteria-inoculated agar. For this, dentin discs (horizontally cut coronal dentin) of 500 μm and 1000 μm thicknesses were produced and irradiated with the laser with irradiation parameters of 0.7-1 W in a cw-mode and exposure times of between 5-30 s. Based on the different sample thicknesses, the penetration depth effect of the irradiation was ascertained after the subsequent incubation of the bacteria-inoculated agar. Additional influential parameters on the irradiation transmission were investigated, including surface moisture, tooth color as well as the presence of a smear layer on the dentin surface.Results: The optical transmission values of the laser radiation for dentin were significantly dependent on the sample thickness (P = 0.006) as well as its moisture content (P = 0.013) and were independent of the presence of a smear layer. There was a 40% reduction in bacteria after the radiography of the 500-μm-thick dentin samples, which was shown as the lowest laser dose (443 J/cm2).Conclusion: These findings indicate that the diode laser with light emission at a wavelength of 445 nm is interesting for the supportive cavity disinfection within the scope of caries therapy and show potential for clinical applications

    Logical Networks: Self-organizing Overlay Networks and Overlay Computing Systems: [EPI Proposal V2.0]

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    Contents 1 Team on March 15, 2010 ...........................................42 Capsule ...........................................52.1 Slogan and logo............................................ 5 2.2 One equation fits all and keywords ................................. 6 2.3 How to read this proposal ...................................... 63 Vertical view ...........................................63.1 Panorama............................................... 6 3.2 General definitions .......................................... 8 3.3 Virtual organization ......................................... 9 3.4 Execution model ........................................... 94 Horizontal view ...............................................94.1 Panorama............................................... 94.2 Arigatoni overlay network ...................................... 10 4.2.1 Arigatoni units........................................ 10 4.2.2 Virtual organizations in Arigatoni ............................. 12 4.2.3 Resource discovery protocol (RDP)............................. 12 4.2.4 Virtual Intermittent Protocol (VIP) ............................ 13 4.2.5 iNeu: librairies for network computing........................... 144.3 Babelchord, a DHT’s tower ..................................... 144.4 Synapse,interconnecting heterogeneous overlay networks. . . . . . . . . . . . . . . . . . . . . 154.5 Cross-layer overlay design for geo-sensible applications . . . . . . . . . . . . . . . . . . . . . . 175 Diagonal view...............................................175.1 Panorama............................................... 17 5.2 Trees versus graphs: a conflict without a cause .......................... 17 5.3 Fault tolerance ............................................ 18 5.4 Parametricity and universality ................................... 18 5.5 Social networking........................................... 19 5.6 Choice of development platform................................... 19 5.7 Quality metrics for an overlay computer .............................. 19 5.8 Trust and security .......................................... 20 5.9 New models of computations .................................... 216 Topics and time line...............................................226.1 Panorama............................................... 226.2 Topicview............................................... 22 6.2.1 Vertical issues......................................... 22 6.2.2 Horizontal issues ....................................... 22 6.2.3 Diagonalissues........................................ 236.3 Timeview............................................... 23 6.3.1 Short-term .......................................... 23 6.3.2 Medium-term......................................... 24 6.3.3 Long-term........................................... 247 Potential application domains ...........................................247.1 Panorama............................................... 24 7.2 P2P social networks ......................................... 25 7.3 Overlay computer for mobile ad hoc networks........................... 25 7.4 OverStic: the mesh overlay network in Sophia Antipolis ..................... 27 7.5 Reducing the Digital Divide..................................... 28 7.6 GRID applications: scenario for seismic monitoring ....................... 29 7.7 Interconnection of heterogeneous overlay networks ........................ 30 7.8 Toward an overlay network of things (RFID) ........................... 318 Software ...........................................328.1 Panorama............................................... 328.2 Prototype software.......................................... 32 8.2.1 Arigatoni simulator ..................................... 32 8.2.2 Ariwheels........................................... 32 8.2.3 BabelChord.......................................... 36 8.2.4 Synapse............................................ 37 8.2.5 Open-Synapse Client..................................... 38 8.2.6 myTransport Gui....................................... 39 8.2.7 CarPal: a P2P carpooling service ............................. 39 8.2.8 Husky interpreter....................................... 408.3 Potential software .......................................... 41 8.3.1 myMed (in french), see http://www-sop.inria.fr/mymed . . . . . . . . . . . . . . . . 419 Contracts...........................................439.1 INTERREG Alcotra: myMed,2010-2013.............................. 43 9.2 COLOR:JMED,2010 ........................................ 43 9.3 FP6 FET GlobalComputing: IST AEOLUS, 2006-2010 ..................... 43 9.4 JET TEMPUS DEUKS, 2007-2009................................. 4410 Collaborations ...........................................4411 Self assessment ...........................................4411.1 Trivia ................................................. 45 11.2 Conclusions.............................................. 45We propose foundations for generic overlay networks and overlay computing systems. Such overlays are built over a large number of distributed computational agents, virtually organized in colonies or virtual organizations, and ruled by a leader (broker) who is elected democratically (vox populi, vox dei) or imposed by system administrators (primus inter pares). Every agent asks the broker to log in the colony by declaring the resources that can be offered (with variable guarantees). Once logged in, an agent can ask the broker for other resources. Colonies can recursively be considered as evolved agents who can log in an outermost colony governed by another super-leader. Communications and routing intra-colonies goes through a broker-2-broker PKI-based negotiation. Every broker routes intra- and inter- service requests by filtering its resource routing table, and then forwarding the request first inside its colony, and second outside, via the proper super-leader (thus applying an endogenous-first-estrogen- last strategy). Theoretically, queries are formulæ in first-order logic equipped with a small program used to orchestrate and synchronize atomic formulæ (atomic services). When the client agent receives notification of all (or part of) the requested resources, then the real resource exchange is performed directly by the server(s) agents, without any further mediation of the broker, in a pure peer-to-peer fashion. The proposed overlay promotes an intermittent participation in the colony, since peers can appear, disappear, and organize themselves dynamically. This implies that the routing process may lead to failures, because some agents have quit or are temporarily unavailable, or they were logged out manu militari by the broker due to their poor performance or greediness. We aim to design, validate through simulation, and implement these foundations in an overlay network computer system. (From [Liquori-Cosnard TGC-07 paper])

    Beyond foraging: behavioral science and the future of institutional economics

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    Institutions affect economic outcomes, but variation in them cannot be directly linked to environmental factors such as geography, climate, or technological availabilities. Game theoretic approaches, based as they typically are on foraging only assumptions, do not provide an adequate foundation for understanding the intervening role of politics and ideology; nor does the view that culture and institutions are entirely socially constructed. Understanding what institutions are and how they influence behavior requires an approach that is in part biological, focusing on cognitive and behavioral adaptations for social interaction favored in the past by group selection. These adaptations, along with their effects on canalizing social learning, help to explain uniformities in political and social order, and are the bedrock upon which we build cultural and institutional variability

    The Question of Spectrum: Technology, Management, and Regime Change

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    There is general agreement that the traditional command-and-control regulation of radio spectrum by the FCC (and NTIA) has failed. There is no general agreement on which regime should succeed it. Property rights advocates take Ronald Coase's advice that spectrum licenses should be sold off and traded in secondary markets, like any other assets. Commons advocates argue that new technologies cannot be accommodated by a licensing regime (either traditional or property rights) and that a commons regime leads to the most efficient means to deliver useful spectrum to the American public. This article reviews the scholarly history of this controversy, outlines the revolution of FCC thinking, and parses the question of property rights vs. commons into four distinct parts: new technology, spectrum uses, spectrum management, and the overarching legal regime. Advocates on both sides find much to agree about on the first three factors; the disagreement is focused on the choice of overarching regime to most efficiently and effectively make spectrum and its applications available to the American public. There are two feasible regime choices: a property rights regime and a mixed licensed/commons regime subject to regulation. The regime choice depends upon four factors: dispute resolution, transactions costs, tragedies of the commons and anticommons, and flexibility to changing technologies and demands. Each regime is described and analyzed against these four factors. With regard to pure transactions costs, commons may hold an advantage but it appears quite small. For all other factors, the property rights regime holds very substantial advantages relative to the mixed regime. I conclude that the choice comes down to markets vs. regulation as mechanism for allocating resources.
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