Auto-tuning Distributed Stream Processing Systems using Reinforcement Learning

Fine tuning distributed systems is considered to be a craftsmanship, relying on intuition and experience. This becomes even more challenging when the systems need to react in near real time, as streaming engines have to do to maintain pre-agreed service quality metrics. In this article, we present an automated approach that builds on a combination of supervised and reinforcement learning methods to recommend the most appropriate lever configurations based on previous load. With this, streaming engines can be automatically tuned without requiring a human to determine the right way and proper time to deploy them. This opens the door to new configurations that are not being applied today since the complexity of managing these systems has surpassed the abilities of human experts. We show how reinforcement learning systems can find substantially better configurations in less time than their human counterparts and adapt to changing workloads

Non-Linear Multiple Field Interactions Neural Document Ranking

Ranking tasks are usually based on the text of the main body of the page and the actions (clicks) of users on the page. There are other elements that could be leveraged to better contextualise the ranking experience (e.g. text in other fields, query made by the user, images, etc). We present one of the first in-depth analyses of field interaction for multiple field ranking in two separate datasets. While some works have taken advantage of full document structure, some aspects remain unexplored. In this work we build on previous analyses to show how query-field interactions, non-linear field interactions, and the architecture of the underlying neural model affect performance

Disaggregated Memory at the Edge

This paper describes how to augment techniques such as Distributed Shared Memory with recent trends on disaggregated Non Volatile Memory in the data centre so that the combination can be used in an edge environment with potentially volatile and mobile resources. This article identifies the main advantages and challenges, and offers an architectural evolution to incorporate recent research trends into production-ready disaggregated edges. We also present two prototypes showing the feasibility of this proposal

Performance evaluation of SiPM detectors for PET imaging in the presence of magnetic fields

Proceeding of: 2008 IEEE Nuclear Science Symposium Conference Record (NSS '08), Dresden, Germany, 19-25 Oct. 2008The multi-pixel photon counter (MPPC) or silicon photo-multiplier (SiPM), recently introduced as a solid-state photodetector, consists of an array of Geiger-mode photodiodes(microcells). is a promising device for PET thanks to its potential for high photon detection efficiency (PDE) and immunity to high magnetic fields. is also very easy to use, with simple electronic read-out, high gain and small size. In this work we evaluate the performance of three 1 x 1 mm2 and one 6 x 6 mm2 (2 x 2 array) SiPMs offered by Hamamatsu for their use in PET. We examine the dependence of the energy resolution and the gain of these devices on the thermal and reverse bias when coupled to LYSO scintillator crystals. We find that the 400 and 1600 microcells models and the 2 x 2 array are suitable for small size crystals, like those employed in high resolution small animal scanners. The good performance of these devices up to 7 Tesla has also been confirmed.This work was supported in part by the MEC (FPA2007-07393), CDTEAM (CENIT-Ingenio 2010) Ministerio de Industria, Spain, UCM (Grupos UCM: 910059), CPAN (ConsoliderIngenio 2010) CSPD-2007-00042 projects, and the RECAVA-RETIC network

Research challenges in nextgen service orchestration

Fog/edge computing, function as a service, and programmable infrastructures, like software-defined networking or network function virtualisation, are becoming ubiquitously used in modern Information Technology infrastructures. These technologies change the characteristics and capabilities of the underlying computational substrate where services run (e.g. higher volatility, scarcer computational power, or programmability). As a consequence, the nature of the services that can be run on them changes too (smaller codebases, more fragmented state, etc.). These changes bring new requirements for service orchestrators, which need to evolve so as to support new scenarios where a close interaction between service and infrastructure becomes essential to deliver a seamless user experience. Here, we present the challenges brought forward by this new breed of technologies and where current orchestration techniques stand with regards to the new challenges. We also present a set of promising technologies that can help tame this brave new world

Pilot multicenter study to determine the utility of point-of-care ultrasound to predict difficulty of tracheal intubation using videolaryngoscopy with the McGrath™ Mac videolaryngoscope.

BACKGROUND Clinical airway screening tests used to predict difficulties during airway management have low sensitivity and specificity. Point-of-care airway ultrasound has described measurements related to problems with difficult direct laryngoscopy. Nevertheless, the correlation between ultrasound parameters and videolaryngoscopy has not been published yet. The aim of this multicenter, prospective observational pilot study was to evaluate the applicability of clinical parameters and ultrasound measurements to find potential tracheal intubation difficulties when videolaryngoscopy is used. METHODS Preoperatively, six clinical airway assessments were performed: (1) modified Mallampati score, (2) thyromental distance, (3) sternomental distance, (4) interincisal distance, (5) upper lip bite test, and (6) neck circumference. Six ultrasound parameters were measured in awake patients: (1) distance from skin to hyoid bone, (2) distance from skin to epiglottis, (3) hyomental distance in neutral head position, (4) hyomental distance in head-extended position, (5) distance from skin to the deepest part of the palate, and (6) sagittal tongue area. And finally, there was one ultrasound measure obtained in anesthetized patients, the compressed sagittal tongue area during videolaryngoscopy. The difficulty for tracheal intubation using a McGrath™ Mac videolaryngoscope, the percentage of glottic opening, and Cormack-Lehane grade were also assessed. RESULTS In this cohort of 119 subjects, tongue dimensions, particularly the sagittal tongue area, showed a robust association with increased intubation difficulty using videolaryngoscopy. A multiparametric model combining the following three ultrasound variables in awake patients: (a) the distance from skin to epiglottis, (b) the distance from skin to the deepest part of the palate, and (c) the sagittal tongue area, yielded a sensitivity of 92.3%, specificity of 94.5%, positive predictive value of 82.8%, and negative predictive value of 97.8% (p < 0.001). CONCLUSION Point-of-care airway ultrasound emerges as a more useful tool compared to traditional clinical scales to anticipate possible challenges during videolaryngoscopic intubation

Venographic comparison of subcutaneous low-molecular weight heparin with oral anticoagulant therapy in the long-term treatment of deep venous thrombosis

Producción CientíficaPurpose: The primary objective of this study was to evaluate with venography the rate of thrombus regression after a fixed dose of low–molecular weight heparin (LMWH) per day for 3 months compared with oral anticoagulant therapy for deep venous thrombosis (DVT). Secondary endpoints were the comparisons of the efficacy and safety of both treatments. Methods: This study was designed as an open randomized clinical study in a university hospital setting. Of the 165 patients finally enrolled in the study, 85 were assigned LMWH therapy and 80 were assigned oral anticoagulant therapy. In the group randomized to oral anticoagulant therapy, the patients first underwent treatment in the hospital with standard unfractionated heparin and then coumarin for 3 months. Doses were adjusted with laboratory monitoring to maintain the international normalized ratio between 2.0 and 3.0. Patients in the LMWH group were administered subcutaneous injections of fixed doses of 40 mg enoxaparin (4000 anti-Xa units) every 12 hours for 7 days, and after discharge from the hospital, they were administered 40 mg enoxaparin once daily at fixed doses for 3 months without a laboratory control assay. A quantitative venographic score (Marder score) was used to assess the extent of the venous thrombosis, with 0 points indicating no DVT and 40 points indicating total occlusion of all deep veins. The rate of thrombus reduction was defined as the difference in quantitative venographic scores after termination of LMWH or coumarin therapy as compared with the scores obtained on the initial venographic results. The efficacy was defined as the ability to prevent symptomatic extension or recurrence of venous thromboembolism (documented with venograms or serial lung scans). The safety was defined as the occurrence of hemorrhages. Results: After 3 months of treatment, the mean Marder score was significantly decreased in both groups in comparison with the baseline score, although the effect of therapy was significantly better after LMWH therapy (49.4% reduction) than after coumarin therapy (24.5% reduction; P < .001). LMWH therapy and male gender were independently associated with an enhanced resolution of the thrombus. A lower frequency of symptomatic recurrent venous thromboembolism was also shown in patients who underwent treatment with LMWH therapy (9.5%) than with oral anticoagulant therapy (23.7%; P < .05), although this difference was entirely a result of recurrence of DVT. Bleeding complications were significantly fewer in the LMWH group than in the coumarin group (1.1% vs 10%; P < .05). This difference was caused by minor hemorrhages. Coumarin therapy and cancer were independently associated with an enhanced risk of complications. Subcutaneous heparin therapy was well tolerated by all patients. Conclusion: The patients who were allocated to undergo enoxaparin therapy had a significantly greater improvement in their quantitative venographic score, a significantl