1,503 research outputs found

    Iffy Predictions and Proper Expectations

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    What individuates the speech act of prediction? The standard view is that prediction is individuated by the fact that it is the unique speech act that requires future-directed content. We argue against this view and two successor views. We then lay out several other potential strategies for individuating prediction, including the sort of view we favor. We suggest that prediction is individuated normatively and has a special connection to the epistemic standards of expectation. In the process, we advocate some constraints that we think a good theory of prediction should respect

    Astrometry with MCAO: HST-GeMS proper motions in the globular cluster NGC 6681

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    Aims: for the first time the astrometric capabilities of the Multi-Conjugate Adaptive Optics (MCAO) facility GeMS with the GSAOI camera on Gemini-South are tested to quantify the accuracy in determining stellar proper motions in the Galactic globular cluster NGC 6681. Methods: proper motions from HST/ACS for a sample of its stars are already available, and this allows us to construct a distortion-free reference at the epoch of GeMS observations that is used to measure and correct the temporally changing distortions for each GeMS exposure. In this way, we are able to compare the corrected GeMS images with a first-epoch of HST/ACS images to recover the relative proper motion of the Sagittarius dwarf spheroidal galaxy with respect to NGC 6681. Results: we find this to be (\mu_{\alpha}cos\delta, \mu_{\delta}) = (4.09,-3.41) mas/yr, which matches previous HST/ACS measurements with a very good accuracy of 0.03 mas/yr and with a comparable precision (r.m.s of 0.43 mas/yr). Conclusions: this study successfully demonstrates that high-quality proper motions can be measured for quite large fields of view (85 arcsec X 85 arcsec) with MCAO-assisted, ground-based cameras and provides a first, successful test of the performances of GeMS on multi-epoch data.Comment: 5 pages, 4 figures. Accepted for publication by A&A Letter

    Towards Precision Photometry with Extremely Large Telescopes: the Double Subgiant Branch of NGC 1851

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    The Extremely Large Telescopes currently under construction have a collecting area that is an order of magnitude larger than the present largest optical telescopes. For seeing-limited observations the performance will scale as the collecting area but, with the successful use of adaptive optics, for many applications it will scale as D4D^4 (where DD is the diameter of the primary mirror). Central to the success of the ELTs, therefore, is the successful use of multi-conjugate adaptive optics (MCAO) that applies a high degree correction over a field of view larger than the few arcseconds that limits classical adaptive optics systems. In this letter, we report on the analysis of crowded field images taken on the central region of the Galactic globular cluster NGC 1851 in KsK_s band using GeMS at the Gemini South telescope, the only science-grade MCAO system in operation. We use this cluster as a benchmark to verify the ability to achieve precise near-infrared photometry by presenting the deepest KsK_s photometry in crowded fields ever obtained from the ground. We construct a colour-magnitude diagram in combination with the F606W band from HST/ACS. As well as detecting the "knee" in the lower main sequence at Ks20.5K_s\simeq20.5, we also detect the double subgiant branch of NGC 1851, that demonstrates the high photometric accuracy of GeMS in crowded fields.Comment: Accepted for publication in ApJL (3 Sep 2015). A version of the paper with high-res images is available at http://www.astro.uvic.ca/~alan/ms_arxiv_hr.pd

    Bibliometric analysis as mesaure [sic] of long-term performance in pancreatic cancer research.

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    Introduction: Research on pancreatic cancer consists in basic, translational and clinical research. Bibliometric indexes as IF and H-Index have been proposed as measures of quality and performance for medical research. Our goal was to analyze the IF and the 5-years H-Index of the publications about pancreatic cancer research

    Complete intraperitoneal displacement of a double J stent: a first case.

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    OBJECTIVES: Ureteral double-J stents are known to migrate proximally and distally within the urinary tract, while perforation and stent displacement are uncommon. Possible mechanisms of displacement are either original malpositioning with ureteral perforation or subsequent fistula and erosion of the excretory system, due to infection or long permanence of the device. We present the unique case of complete intraperitoneal stent migration in a 59-year-old caucasian male without evidence of urinary fistula at the moment of diagnosis, so far an unreported complication. MATERIALS AND METHODS: Eight months after the placement of a double-J stent for lower right ureteral stricture at a district hospital, the patient came at our observation for urosepsis and hydro-uretero-nephrosis. A CT scan demonstrated intraperitoneal migration of the stent outside the urinary tract. Cystoscopy failed to visualize the lower extremity of the stent, a percutaneous nephrostomy was placed to drain the urinary system and the stent was removed through a small abdominal incision on the right lower quadrant. RESULTS: In our case we presume that during the positioning manoeuvre the guide wire perforated simultaneously the lower ureteral wall and the pelvic peritoneum, and that once the upper end of the stent was coiled, the lower extremity was also attracted intraperitoneally. The lack of pain due to the spinal lesion concurred to this unusual complication. CONCLUSIONS: We must be aware that ureteral double J stents may be found displaced even inside the peritoneal cavity, and that the use of retrograde pyelography during placement is of paramount importance to exclude misplacement of an apparently normally coiled upper extremity of the stent

    Micro market based optimisation framework for decentralised management of distributed flexibility assets

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    Continuously changing electricity demand and intermittent renewable energy sources pose challenges to the operation of power systems. An alternative to reinforcing the grid infrastructure is to deploy and manage distributed energy storage systems. In this work, a micro-energy market is proposed for smart domestic energy trading in the low-voltage distribution systems in the context of high penetration of photovoltaic systems and battery energy storage systems. In addition, a micro-balancing market is proposed to address the congestions due to unforeseen energy imbalance. Centralised and decentralised management strategies are simulated in real time, based on generation and demand forecasts. In addition, electric vehicles are also simulated as potential storage solutions to improve grid operation. A techno-economic evaluation informs key stakeholders, in particular grid operators on strategies for a sustainable implementation of the proposed strategies. The results show that the micro-energy market reduces the energy cost for all grid users by 4.1–20.2%, depending on their configuration. In addition, voltage deviation, peak electricity demand and reverse power flow have been reduced by 12.8%, 7.7% and 85.6% respectively, with the proposed management strategies. The micro-balancing market has been demonstrated to keep the voltage profile and thermal characteristic within the set limit in case of contingency

    The Low Energy Tagger for the KLOE-2 experiment

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    The KLOE experiment at the upgraded DAFNE e+e- collider in Frascati (KLOE-2) is going to start a new data taking at the beginning of 2010 with its detector upgraded with a tagging system for the identification of gamma-gamma interactions. The tagging stations for low-energy e+e- will consist in two calorimeters The calorimeter used to detect low-energy e+e- will be placed between the beam-pipe outer support structure and the inner wall of the KLOE drift chamber. This calorimeter will be made of LYSO crystals readout by Silicon Photomultipliers, to achieve an energy resolution better than 8% at 200 MeV.Comment: 4 pages, 5 figures, in the proceedings of "Frontier detectors for frontier physics", isola d'Elba, Italy, May 200
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