527 research outputs found

    Introduction to neutrino astronomy

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    This writeup is an introduction to neutrino astronomy, addressed to astronomers and written by astroparticle physicists. While the focus is on achievements and goals in neutrino astronomy, rather than on the aspects connected to particle physics, we will introduce the particle physics concepts needed to appreciate those aspects that depend on the peculiarity of the neutrinos. The detailed layout is as follows: In Sect.~1, we introduce the neutrinos, examine their interactions, and present neutrino detectors and telescopes. In Sect.~2, we discuss solar neutrinos, that have been detected and are matter of intense (theoretical and experimental) studies. In Sect.~3, we focus on supernova neutrinos, that inform us on a very dramatic astrophysical event and can tell us a lot on the phenomenon of gravitational collapse. In Sect.~4, we discuss the highest energy neutrinos, a very recent and lively research field. In Sect.~5, we review the phenomenon of neutrino oscillations and assess its relevance for neutrino astronomy. Finally, we offer a brief overall assessment and a summary in Sect.~6. The material is selected - i.e., not all achievements are reviewed - and furthermore it is kept to an introductory level, but efforts are made to highlight current research issues. In order to help the beginner, we prefer to limit the list of references, opting whenever possible for review works and books.Comment: 15 pages, 5 figures. Accepted for publication The European Physical Journal Plus. Based on the lecture given at the "4th Azarquiel School of Astronomy", June 2017, Porto Paolo di Capo Passero, Syracuse (Italy) https://agenda.infn.it/conferenceDisplay.py?confId=1208

    Supernova neutrino physics with a nuclear emulsion detector

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    The existence of the coherent neutrino-nucleus scattering reaction requires to evaluate, for any detector devoted to WIMP searches, the irreducible background due to conventional neutrino sources and at same time, it gives a unique chance to reveal supernova neutrinos. We report here a detailed study concerning a new directional detector, based on the nuclear emulsion technology. A Likelihood Ratio test shows that, in the first years of operations and with a detector mass of several tens of tons, the observation of the supernova signal can be achieved. The determination of the distance of the supernova from the neutrinos and the observation of 8^8B neutrinos are also discussed.Comment: 22 pages, 12 figure

    Visitor-sensing: Involving the crowd in cultural heritage organizations

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    As organizations are increasingly involving individuals across their boundaries in the generation of new knowledge, crowd involvement can also be beneficial to cultural heritage organizations. We argue that in an "Open Innovation in Science" approach, visitors can contribute to generate new scientific knowledge concerning their behavior and preferences, by which museum managers can re-design the cultural offerings of their institutions in ways that generate major economic and social impacts. Accordingly, we advance visitor-sensing as a novel framework in which museum managers leverage digital technologies to collect visitors' ideas, preferences, and feedback in order to improve path design and the organization of artwork in exhibitions, and to shape a more satisfying museum experience for visitors. We contend that visitor-sensing has the potential to yield higher numbers of visitors, with positive impacts in terms of increased revenues and increased literacy of the general public, thus benefiting the economic and social sustainability of cultural organizations towards the achievement of the Sustainable Development Goals outlined in the Agenda 2030

    Refined Structure of Metastable Ice XVII from Neutron Diffraction Measurements

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    The structure of the recently identified metastable ice XVII, obtained by release of hydrogen from the C0_0 D2_2O-H2_2 compound (filled ice), has been accurately measured by neutron powder diffraction. The diffraction pattern is indexed with a hexagonal cell and can be refined with space group P6122P6_122 so to obtain accurate values of the oxygen and deuterium positions. The values of the lattice constants at three temperatures between 25 to 100 K are reported, and their behavior is compared with that of ice Ih. Ice XVII is a porous solid that, if exposed to H2_2 gas, may adsorb a substantial amount of it. Monitoring this effect at a constant temperature of 50 K, we have observed that the two lattice constants show opposite behavior, aa increases and cc decreases, with the volume showing a linear increase. At temperatures higher than 130 K the metastability of this form of porous ice is lost and the sample transforms into ice Ih

    How subjective and non-physical parameters affect occupants’ environmental comfort perception

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    Employees’ wellbeing and comfort perception demonstrated to largely influence their productivity and tolerability of slight thermal discomfort conditions in the working spaces. Their whole comfort perception indeed depends on several parameters related to physical boundary conditions but also to the adaptation capability of occupants themselves and other personal, difficult to measure, variables. According to the available standards and regulations, only physical and measurable environmental parameters must be considered to evaluate occupants’ comfort conditions. Therefore, non-measurable factors such as socio-psychological, physiological, medical ones are currently not systematically considered. The present work aims to identify possible benefits in terms of occupants’ comfort perception due to non-physical strategies aimed at improving the work-environment quality and livability. To this aim, the environmental multi-physics and multi-domain performance of a mixed industry-office building is investigated through coupled in-field microclimate monitoring and questionnaires campaigns. The experimental microclimate monitoring and survey campaign were carried out to understand (i) the realistic indoor environmental conditions in terms of physical and measurable parameters and (ii) the personal perceptions and attitudes of the occupants with respect to those same ambient parameters, including also acoustic, lighting and medical investigation. Moreover, the collected experimental data were used to determine occupants’ comfort level through the classic comfort models, to be compared to the identified role of non-physical parameters on occupants’ final perception about the indoor environment. The main results show that non-measurable factors induced by virtuous company policy to improve employees’ working environment are effectively able to positively influence their whole-comfort perception even if the majority of workers do not have the opportunity to control their working environment. In fact, the consolidated comfort theories underestimate people satisfaction, as demonstrated by more than the 80% employees, who declared to be positively influenced by the pleasant aesthetics and livability of the workplace. The year-round experimental campaign demonstrated the need to further investigate the key role of non-physical parameters for possible incorporation into whole-comfort prediction models and standards. The role of such strategies could therefore be realistically considered as energy saving opportunities since they make building occupants much more open to tolerate slight uncomfortable conditions

    Middle Stone Age Ochre Processing and Behavioural Complexity in the Horn of Africa : Evidence from Porc-Epic Cave, Dire Dawa, Ethiopia

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    Ochre is a common feature at Middle Stone Age (MSA) sites and has often been interpreted as a proxy for the origin of modern behaviour. However, few ochre processing tools, ochre containers, and ochre-stained artefacts from MSA contexts have been studied in detail within a theoretical framework aimed at inferring the technical steps involved in the acquisition, production and use of these artefacts. Here we analyse 21 ochre processing tools, i.e. upper and lower grindstones, and two ochre-stained artefacts from the MSA layers of Porc-Epic Cave, Dire Dawa, Ethiopia, dated to ca. 40 cal kyr BP. These tools, and a large proportion of the 4213 ochre fragments found at the site, were concentrated in an area devoted to ochre processing. Lower grindstones are made of a variety of raw materials, some of which are not locally available. Traces of use indicate that different techniques were employed to process ochre. Optical microscopy, XRD, ÎĽ-Raman spectroscopy, and SEM-EDS analyses of residues preserved on worn areas of artefacts show that different types of ferruginous rocks were processed in order to produce ochre powder of different coarseness and shades. A round stone bearing no traces of having been used to process ochre is half covered with residues as if it had been dipped in a liquid ochered medium to paint the object or to use it as a stamp to apply pigment to a soft material. We argue that the ochre reduction sequences identified at Porc-Epic Cave reflect a high degree of behavioural complexity, and represent ochre use, which was probably devoted to a variety of functions

    Extracting Graph Topological Information and Users’ Opinion

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    This paper focuses on the role of social relations within social media in the formation of public opinion. We propose to combine the detection of the users’ stance towards BREXIT, carried out by content analysis of Twitter messages, and the exploration of their social relations, by relying on social network analysis. The analysis of a novel Twitter corpus on the BREXIT debate, developed for our purposes, shows that like-minded individuals (sharing the same opinion towards the specific issue) are likely belonging to the same social network community. Moreover, opinion driven homophily is exhibited among neighbours. Interestingly, users’ stance shows diachronic evolution

    Use of tranexamic acid in total knee arthroplasty

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    PURPOSE: different strategies have been developed to reduce blood loss in total knee arthroplasty (TKA). The efficacy of both systemic and local tranexamic acid (TXA) administration is demonstrated in the literature. The aim of the present study was to compare the efficacy of systemic, local and combined (systemic + local) administration of TXA in reducing blood loss after TKA. METHODS: we enrolled all patients submitted to a primary TKA in our department between November 2014 and August 2015. They were divided into three groups corresponding to the method of TXA administration used: intravenous (IV), intra-articular (IA), and a combination of the two. Demographic data, as well as preoperative hemoglobin and platelet levels, were collected. The primary outcome was the maximum hemoglobin loss, while the secondary outcomes were the amount of blood in the drain (cc/hour) and the rate of transfusions; postoperative pain was also assessed. Student’s t-test or a χ(2) test was used to evaluate between-group differences, using p<0.05 as the cut-off for statistically significant differences. RESULTS: the sample comprised 34 patients: IV, 10 cases; IA, 15 cases, and combined (IV + IA), 9 cases. The average age of the patients was 71.1±6.4 years. No significant differences in the outcome measures were found between the groups, with the exception of a significantly lower maximum hemoglobin loss in the combined versus the IV group (p=0.02). There were no differences between the groups in the amount of blood in the drain or the rate of transfusions. CONCLUSIONS: the data from this preliminary study, as well as data from the literature, confirm that TXA administration is safe and effective in reducing total blood loss in TKA, and no administration protocol seems to be superior to the others. LEVEL OF EVIDENCE: Level II, prospective comparative study

    Un método automático para la desambiguación léxica de nombres

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    Este art&iacute;culo presenta un m&eacute;todo completamente autom&aacute;tico que resuelve la desambiguaci&oacute;n l&eacute;xica de nombres calculando la densidad conceptual de cada uno de los sentidos del nombre a desambiguar. La evaluaci&oacute;n del m&eacute;todo se ha realizado sobre el corpus SemCor con un contexto de s&oacute;lo dos nombres, obteniendo una precisi&oacute;n de 81.5% y un recall de 60.25%.Palabras clave: desambiguaci&oacute;n l&eacute;xica de nombres, densidad conceptual
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