784 research outputs found

    Outsourcing labour to the cloud

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    Various forms of open sourcing to the online population are establishing themselves as cheap, effective methods of getting work done. These have revolutionised the traditional methods for innovation and have contributed to the enrichment of the concept of 'open innovation'. To date, the literature concerning this emerging topic has been spread across a diverse number of media, disciplines and academic journals. This paper attempts for the first time to survey the emerging phenomenon of open outsourcing of work to the internet using 'cloud computing'. The paper describes the volunteer origins and recent commercialisation of this business service. It then surveys the current platforms, applications and academic literature. Based on this, a generic classification for crowdsourcing tasks and a number of performance metrics are proposed. After discussing strengths and limitations, the paper concludes with an agenda for academic research in this new area

    Geometric reasoning via internet crowdsourcing

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    The ability to interpret and reason about shapes is a peculiarly human capability that has proven difficult to reproduce algorithmically. So despite the fact that geometric modeling technology has made significant advances in the representation, display and modification of shapes, there have only been incremental advances in geometric reasoning. For example, although today's CAD systems can confidently identify isolated cylindrical holes, they struggle with more ambiguous tasks such as the identification of partial symmetries or similarities in arbitrary geometries. Even well defined problems such as 2D shape nesting or 3D packing generally resist elegant solution and rely instead on brute force explorations of a subset of the many possible solutions. Identifying economic ways to solving such problems would result in significant productivity gains across a wide range of industrial applications. The authors hypothesize that Internet Crowdsourcing might provide a pragmatic way of removing many geometric reasoning bottlenecks.This paper reports the results of experiments conducted with Amazon's mTurk site and designed to determine the feasibility of using Internet Crowdsourcing to carry out geometric reasoning tasks as well as establish some benchmark data for the quality, speed and costs of using this approach.After describing the general architecture and terminology of the mTurk Crowdsourcing system, the paper details the implementation and results of the following three investigations; 1) the identification of "Canonical" viewpoints for individual shapes, 2) the quantification of "similarity" relationships with-in collections of 3D models and 3) the efficient packing of 2D Strips into rectangular areas. The paper concludes with a discussion of the possibilities and limitations of the approach

    Multilobar electrocorticography monitoring during intracranial aneurysm surgery

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    Introduction: To detect a neuronal threshold of tolerance to ischemia, the usefulness of multilobar electrocorticography (mEcoG) during intracranial aneurysm surgery was compared to the scalp EEG and correlated with the postoperative neurological status and the radiological findings. Methods: Twenty-one patients harboring intracranial aneurysms were monitored by simultaneous scalp EEG and lobe-dependent mEcoG during surgical clipping. The patients were divided into group A (6 patients with no temporary clipping) and group B (15 patients with temporary clipping). Results: New focal modifications of the mEcoG signal with high frequency (HF)-β3 and delta waves were observed in none of the patients in group A and all of the patients in group B. These anomalies were followed by focal burst suppression pattern in eight cases (53%) in group B. These changes were detected in only two cases (9%) on the scalp EEG. New corticographic changes resolved in eight patients (53%) in group B. Among the seven patients in group B who had persistent focal burst pattern after clip removal, six (85%) presented with new neurological deficit or new hypodensity on CT. The Glasgow Outcome Scale was good (IV or V) in 85% of cases. Conclusion: mEcoG is more sensitive than scalp EEG. The appearance and persistence of the focal burst suppression pattern shown on mEcoG, was associated with a new neurological deficit or new hypodensity, whereas HF-β3 or delta waves per se were not associated with new changes. A better comprehension of these EEG anomalies could determine the duration of temporary clipping and consequently influence the surgical strateg

    Validation of purdue engineering shape benchmark clusters by crowdsourcing

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    The effective organization of CAD data archives is central to PLM and consequently content based retrieval of 2D drawings and 3D models is often seen as a "holy grail" for the industry. Given this context, it is not surprising that the vision of a "Google for shape", which enables engineers to search databases of 3D models for components similar in shape to a query part, has motivated numerous researchers to investigate algorithms for computing geometric similarity. Measuring the effectiveness of the many approaches proposed has in turn lead to the creation of benchmark datasets against which researchers can compare the performance of their search engines. However to be useful the datasets used to measure the effectiveness of 3D retrieval algorithms must not only define a collection of models, but also provide a canonical specification of their relative similarity. Because the objective of shape retrieval algorithms is (typically) to retrieve groups of objects that humans perceive as "similar" these benchmark similarity relationships have (by definition) to be manually determined through inspection

    Effect of obesity and thoracic epidural analgesia on perioperative spirometry

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    Background. Lung volumes in obese patients are reduced significantly in the postoperative period. As the effect of different analgesic regimes on perioperative spirometric tests in obese patients has not yet been studied, we investigated the effect of thoracic epidural analgesia and conventional opioid-based analgesia on perioperative lung volumes measured by spirometry. Methods. Eighty-four patients having midline laparotomy for gynaecological procedures successfully completed the study. Premedication, anaesthesia and analgesia were standardized. The patients were given a free choice between epidural analgesia (EDA) (n=42) or opioids (n=42) for postoperative analgesia. We performed spirometry to measure vital capacity (VC), forced vital capacity, peak expiratory flow, mid-expiratory flow and forced expiratory volume in 1 s at preoperative assessment, 30-60 min after premedication and 20 min, 1 h, 3 h and 6 h after extubation. Results. Baseline values were all within the normal range. All perioperative spirometric values decreased significantly with increasing body mass index (BMI). The greatest reduction in VC occurred directly after extubation, but was less in the EDA group than in the opioid group: mean of −23(sd 8)% versus −30(12)% (P30) the difference in VC was significantly more pronounced than in patients of normal weight (BMI<25): −45(10)% versus −33(4)% (P<0.001). Recovery of spirometric values was significantly quicker in patients receiving EDA, particularly in obese patients. Conclusion. We conclude that EDA should be considered in obese patients undergoing midline laparotomy to improve postoperative spirometr

    Radiosurgery for trigeminal neuralgia using a linear accelerator with BrainLab system: report on initial experience in Lausanne, Switzerland

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    BACKGROUND/AIMS: Radiosurgery is an effective treatment for trigeminal neuralgia (TN) with minimal complications. Most experience is based on gamma knife radiosurgery (GKRS) and to a lesser extent on linear accelerators. METHODS: We report our initial experience in 17 patients with TN treated by an adapted linear accelerator using the BrainLab system. The trigeminal root entry zone immediately adjacent to the pons (target volume: 0.01-0.09 cm3, mean: 0.02 cm3) was targeted by use of a multileaf collimator to deliver 40-45 Gy to the 80% isodose (dose max 50-56 Gy). Median follow-up was 12 months (range: 1-60). RESULTS: All patients reported some initial improvement in level of pain after treatment (mean time: 1 month). Initial pain responses were as follows: 6 patients (35%) had complete pain relief and required no medication, 6 (35%) had occasional pain but were off medication, and 5 (30%) experienced partial relief of pain but still required medication, usually in lower doses. Five patients (29%) who experienced initial pain relief had recurrences ranging from 4-13 months after procedure. There were no major or minor complications of radiosurgery except one case of mild facial itching. CONCLUSION: Stereotactic radiosurgery using a linear accelerator appears to be effective and can be a favourable alternative to other procedures, including GKRS. The procedure is very safe and side effects are rare and minor. However, a randomised trial with a longer follow-up comparing radiosurgery to other surgical procedures is needed to assess the long term effectiveness of this treatmen

    Effect of obesity and site of surgery on perioperative lung volumes

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    Background. Although obese patients are thought to be susceptible to postoperative pulmonary complications, there are only limited data on the relationship between obesity and lung volumes after surgery. We studied how surgery and obesity affect lung volumes measured by spirometry. Methods. We prospectively studied 161 patients having either breast surgery (Group A, n=80) or lower abdominal laparotomy (Group B, n=81). Premedication and general anaesthesia were standardized. Spirometry was measured with the patient supine, in a 30° head‐up position. We measured vital capacity (VC), forced vital capacity, peak expiratory flow and forced expiratory volume in 1 s at preoperative assessment (baseline), after premedication (before induction of anaesthesia) and 10-20 min, 1 h and 3 h after extubation. Results. Baseline spirometric values were all within the normal range. All perioperative values decreased significantly with increasing body mass index (BMI). The greatest reduction of mean VC (expressed as percentage of baseline values) occurred after extubation, and was more marked after laparotomy than after breast surgery (23 (sd 14)% vs 20 (14)%). Considering patients according to BMI (30), VC decreased after surgery by 12 (7)%, 24 (8)% and 40 (10)%, respectively. VC recovered more rapidly in Group A. Conclusion. Postoperative reduction in spirometric volumes was related to BMI. Obesity had more effect on VC than the site of surgery. Br J Anaesth 2004; 92: 202-

    The porin and the permeating antibiotic: A selective diffusion barrier in gram-negative bacteria

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    Gram-negative bacteria are responsible for a large proportion of antibiotic resistant bacterial diseases. These bacteria have a complex cell envelope that comprises an outer membrane and an inner membrane that delimit the periplasm. The outer membrane contains various protein channels, called porins, which are involved in the influx of various compounds, including several classes of antibiotics. Bacterial adaptation to reduce influx through porins is an increasing problem worldwide that contributes, together with efflux systems, to the emergence and dissemination of antibiotic resistance. An exciting challenge is to decipher the genetic and molecular basis of membrane impermeability as a bacterial resistance mechanism. This Review outlines the bacterial response towards antibiotic stress on altered membrane permeability and discusses recent advances in molecular approaches that are improving our knowledge of the physico-chemical parameters that govern the translocation of antibiotics through porin channel
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