232 research outputs found

    Poder y escritura : el Príncipe, la biblioteca y la dedicatoria (siglos XV-XVII)

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    Se muestra cómo la lectura y la escritura son actos sociales perfectamente normativizados en la cultura de la Edad Moderna. Se exponen los ejemplos de la biblioteca, una institución en la que tan importante como el material que conserva son las relaciones sociales que se establecen entorno a ella (así en las "bibliotecas reales" como en las particulares), y de la dedicatoria de libros, en la que los autores desarrollan un lenguage muy sutil que les permitía relacionarse de forma especial con el destinatario.Roger Chartier shows how reading and writing were perfectly normativized social acts in the culture of Modern Age. As a demonstration of his assertions, he sets two examples: the first concerning libraries, institutions where materials preserved there were as important as social relationship established round it (both in regal libraries and in private ones), the second about the dedications written in books, through which their authors developed a very subtle language that allowed them to set up a kind of especial relation with their final addressees

    Removing krypton from xenon by cryogenic distillation to the ppq level

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    The XENON1T experiment aims for the direct detection of dark matter in a cryostat filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by radioactive decays inside the detector has to be sufficiently low. One major contributor is the β\beta-emitter 85^{85}Kr which is an intrinsic contamination of the xenon. For the XENON1T experiment a concentration of natural krypton in xenon nat\rm{^{nat}}Kr/Xe < 200 ppq (parts per quadrillion, 1 ppq = 1015^{-15} mol/mol) is required. In this work, the design of a novel cryogenic distillation column using the common McCabe-Thiele approach is described. The system demonstrated a krypton reduction factor of 6.4\cdot105^5 with thermodynamic stability at process speeds above 3 kg/h. The resulting concentration of nat\rm{^{nat}}Kr/Xe < 26 ppq is the lowest ever achieved, almost one order of magnitude below the requirements for XENON1T and even sufficient for future dark matter experiments using liquid xenon, such as XENONnT and DARWIN

    The ANTARES Optical Beacon System

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    ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.Comment: 21 pages, 18 figures, submitted to Nucl. Instr. and Meth. Phys. Res.

    Search for Two-Neutrino Double Electron Capture of 124^{124}Xe with XENON100

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    Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shell. For 124^{124}Xe this process has not yet been observed and its detection would provide a new reference for nuclear matrix element calculations. We have conducted a search for two-neutrino double electron capture from the K-shell of 124^{124}Xe using 7636 kg\cdotd of data from the XENON100 dark matter detector. Using a Bayesian analysis we observed no significant excess above background, leading to a lower 90 % credibility limit on the half-life T1/2>6.5×1020T_{1/2}>6.5\times10^{20} yr. We also evaluated the sensitivity of the XENON1T experiment, which is currently being commissioned, and find a sensitivity of T1/2>6.1×1022T_{1/2}>6.1\times10^{22} yr after an exposure of 2 t\cdotyr.Comment: 6 pages, 4 figure

    Key Ergonomics Requirements and Possible Mechanical Solutions for Augmented Reality Head-Mounted Displays in Surgery

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    In the context of a European project, we identified over 150 requirements for the development of an augmented reality (AR) head-mounted display (HMD) specifically tailored to support highly challenging manual surgical procedures. The requirements were established by surgeons from different specialties and by industrial players working in the surgical field who had strong commitments to the exploitation of this technology. Some of these requirements were specific to the project, while others can be seen as key requirements for the implementation of an efficient and reliable AR headset to be used to support manual activities in the peripersonal space. The aim of this work is to describe these ergonomic requirements that impact the mechanical design of the HMDs, the possible innovative solutions to these requirements, and how these solutions have been used to implement the AR headset in surgical navigation. We also report the results of a preliminary qualitative evaluation of the AR headset by three surgeons

    Deep sea tests of a prototype of the KM3NeT digital optical module

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    The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been deployed in the deepwaters of the Mediterranean Sea. This digital optical module has a novel design with a very large photocathode area segmented by the use of 31 three inch photomultiplier tubes. It has been integrated in the ANTARES detector for in-situ testing and validation. This paper reports on the first months of data taking and rate measurements. The analysis results highlight the capabilities of the new module design in terms of background suppression and signal recognition. The directionality of the optical module enables the recognition of multiple Cherenkov photons from the same (40)Kdecay and the localisation of bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions

    First results of the Instrumentation Line for the deep-sea ANTARES neutrino telescope

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    In 2005, the ANTARES Collaboration deployed and operated at a depth of 2500 m a so-called Mini Instrumentation Line equipped with Optical Modules (MILOM) at the ANTARES site. The various data acquired during the continuous operation from April to December 2005 of the MILOM confirm the satisfactory performance of the Optical Modules, their front-end electronics and readout system. as well as the calibration devices of the detector. The in situ measurement of the Optical Module time response yields a resolution better than 0.5 ns. The performance of the acoustic positioning system, which enables the spatial reconstruction of the ANTARES detector with a precision of about 10 cm, is verified. These results demonstrate that with the full ANTARES neutrino telescope the design angular resolution of better than 0.3 degrees can be realistically achieved

    Actual physical activity after major abdominal cancer surgery:Far from optimal

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    BACKGROUND: Enhanced recovery after surgery protocols emphasize the importance of early postoperative mobilization. However, literature quantifying actual physical activity after major abdominal cancer surgery is scarce and inconclusive.MATERIAL AND METHODS: A single-center prospective cohort study was conducted at the University Medical Center Groningen from 2019 to 2021. Patients' postoperative physical activity was measured using an accelerometer, with the primary aim of assessing daily physical activity. Secondary aims were identifying patient-related factors associated with low physical activity and studying the consequences of low physical activity in terms of complication rate and length of hospital stay.RESULTS: 143 patients included (48 % male; mean age 65 years), 38.5 %, 24.5 %, 19.6 %, and 14 % underwent pancreatic, hepatic, colorectal, or cytoreductive surgery with hyperthermic intraperitoneal chemotherapy, respectively. Median daily step count was low; from median 71 steps on the first to 918 steps on the seventh postoperative day. An association between physical activity and age (OR 3.597, p = 0.013), preoperative weight loss ≥10 % (OR 4.984, p = 0.004), Eastern Cooperative Oncology Group performance status ≥2 (OR 4.016, p = 0.001), midline laparotomy (OR 2.851, p = 0.025), and operation duration (OR 1.003, p = 0.044) was found. An association was observed between physical activity and the occurrence of complications (OR 3.197, p = 0.039) and prolonged hospital stay (β 4.068, p = 0.013).CONCLUSION: Postoperative physical activity is low in patients undergoing major abdominal cancer surgery and is linked to postoperative outcomes. Although physical activity should be encouraged in all patients, patient-specific risk factors were identified that can aid early recognition of patients at risk of low physical activity.</p

    Nutritional support in pancreatic cancer patients and its effect on nutritional status:an observational regional HPB network study investigating current practice

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    PURPOSE: Preoperative malnutrition is associated with poor postoperative outcomes in patients with pancreatic cancer. This study evaluated the effectiveness of current practice in nutritional support for patients with pancreatic cancer.METHODS: Observational multicenter HPB network study conducted at the Isala Clinics Zwolle, Medical Spectrum Twente, Medical Center Leeuwarden, and University Medical Center Groningen between October 2021 and May 2023. Patients with a suspected pancreatic malignancy scheduled for surgery were screened for malnutrition using the Patient-Generated Subjective Global Assessment (PG-SGA) questionnaire and referred to a dedicated dietician for nutritional support comprising pancreatic enzyme replacement therapy, dietary advice, and nutritional supplements to achieve adequate caloric and protein intake. At baseline, 1 day preoperatively, and 3 months postoperatively, the nutritional status and muscle thickness were evaluated.RESULTS: The study included 30 patients, of whom 12 (40%) classified as malnourished (PG-SGA ≥ 4) at baseline. Compared to well-nourished patients, malnourished patients were younger, were predominantly female, and had a higher body mass index, despite having lost more body weight in the past 6 months. All malnourished patients and 78% of the well-nourished patients received nutritional support. Consequently, a preoperative increase in caloric and protein intake and body weight were observed. Postoperatively, despite a further increase in caloric intake, a considerable decrease in protein intake, body weight, and muscle thickness was observed.CONCLUSION: Malnutrition is prevalent in patients undergoing pancreatic surgery. Nutritional support by a dedicated dietician is effective in enhancing patients' preoperative nutritional status. However, postoperative monitoring of adequate nutritional intake in patients could be improved.</p
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