869 research outputs found

    Colloidal CuFeS2 Nanocrystals: Intermediate Fe d-Band Leads to High Photothermal Conversion Efficiency

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    We describe the colloidal hot-injection synthesis of phase-pure nanocrystals (NCs) of a highly abundant mineral, chalcopyrite (CuFeS2). Absorption bands centered at around 480 and 950 nm, spanning almost the entire visible and near infrared regions, encompass their optical extinction characteristics. These peaks are ascribable to electronic transitions from the valence band (VB) to the empty intermediate band (IB), located in the fundamental gap and mainly composed of Fe 3d orbitals. Laser-irradiation (at 808 nm) of an aqueous suspension of CuFeS2 NCs exhibited significant heating, with a photothermal conversion efficiency of 49%. Such efficient heating is ascribable to the carrier relaxation within the broad IB band (owing to the indirect VB-IB gap), as corroborated by transient absorption measurements. The intense absorption and high photothermal transduction efficiency (PTE) of these NCs in the so-called biological window (650-900 nm) makes them suitable for photothermal therapy as demonstrated by tumor cell annihilation upon laser irradiation. The otherwise harmless nature of these NCs in dark conditions was confirmed by in vitro toxicity tests on two different cell lines. The presence of the deep Fe levels constituting the IB is the origin of such enhanced PTE, which can be used to design other high performing NC photothermal agents.Comment: 12 pages, Chemistry of Materials, 31-May-201

    From the deposit to the exhibit floor: an exploration on giving museum objects personality and social life

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    Museum objects have fascinating stories but are often presented in a detached, objective way that tends to keep visitors at a distance. In a collaborative research we have explored a different way to present museum objects: fifteen exhibits from the museum deposit compete for one of the four display cases on the exhibit floor. Objects are given a personal voice and a character and they talk directly to the visitor: those that capture visitors' interest as physical presence or Twitter conversation stay on display; the lower scorer is replaced. We report the co-design and preliminary evaluation carried out in the museum with both museum professionals and casual visitors

    The diet of otters (Lutra lutra) on the Agri river system, one of the most important presence sites in Italy: A molecular approach

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    Background. The Eurasian otter (Lutra lutra) underwent a strong decline in large areas of the Central-Western part of its distribution range, during the second half of the twentieth century. In Italy, only residual fragmented nuclei survive in the Central- Southern part of the peninsula. Nowadays, the otter is one of the most endangered mammals in Italy, and increasing the knowledge about the ecology of this species is a key step in defining fitting management strategies. Here we provide information about the diet of otter on the Agri river system, one of the most important presence sites in Italy, to understand both the species' food requirements and the impact on fish communities. Methods. DNA metabarcoding and High Throughput Sequencing were used on DNA extracted from spraints. We amplified DNA with a primer set for vertebrates, focusing efforts on the bulk of the otter's diet (fishes and amphibians). Results. Our findings showed that the diet of the otter was dominated by cyprinids (97.77%, and 99.14% of fishes), while amphibians represented 0.85% of the sequences analyzed. Results are in general accordance with previous studies based on morphological characterization; however, molecular analyses allow the resolving of some morphological uncertainties. Although the study area offers a very wide range of available prey, the diet of the otters shows marked selectivity. We highlighted a variation in prey consumed, in accordance with the typology of water system (i.e., river, lake, tributary). Some of the preys found in the diet were alien species introduced by man for sport fishing. Our findings could help define strategies useful for the conservation of the otter population in Southern Italy, suggesting management actions directed at avoiding fish community alterations through illegal stockings without severe controls on their taxonomic status. These introductions could result in a general reduction in the diversity of the otter's preys, affecting its predatory behavior

    User-centred design of flexible hypermedia for a mobile guide: Reflections on the hyperaudio experience

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    A user-centred design approach involves end-users from the very beginning. Considering users at the early stages compels designers to think in terms of utility and usability and helps develop the system on what is actually needed. This paper discusses the case of HyperAudio, a context-sensitive adaptive and mobile guide to museums developed in the late 90s. User requirements were collected via a survey to understand visitors’ profiles and visit styles in Natural Science museums. The knowledge acquired supported the specification of system requirements, helping defining user model, data structure and adaptive behaviour of the system. User requirements guided the design decisions on what could be implemented by using simple adaptable triggers and what instead needed more sophisticated adaptive techniques, a fundamental choice when all the computation must be done on a PDA. Graphical and interactive environments for developing and testing complex adaptive systems are discussed as a further step towards an iterative design that considers the user interaction a central point. The paper discusses how such an environment allows designers and developers to experiment with different system’s behaviours and to widely test it under realistic conditions by simulation of the actual context evolving over time. The understanding gained in HyperAudio is then considered in the perspective of the developments that followed that first experience: our findings seem still valid despite the passed time

    Metformin and Covid-19: a systematic review of systematic reviews with meta-analysis

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    : the COVID-19 infection, caused by severe Coronavirus 2 syndrome (Sars-Cov-2), immediately appeared to be the most tragic global pandemic event of the twentieth century. Right from the start of the pandemic, diabetic patients treated with metformin experienced a reduction in mortality and complications from COVID-19 compared to those with different treatments or no treatment. Objective The main objective of the study was to observe the effects of metformin in hospitalized subjects infected with COVID-19. Specifically, the outcomes of hospitalization in Intensive Care Units or death were examined. Materials and Methods A specific research PICOS was developed and the Pubmed, Embase and Scopus databases were consulted down to April 30, 2022. To estimate the extent of the metformin effect and risk of severity in SARS-CoV-2 infection, the Odd Ratio (OR) with 95% Confidence Interval (CI) published by the authors of the selected systematic reviews was used. Results from five systematic reviews 36 studies were selected. The final meta-analysis showed that thanks to treatment with metformin, DM2 patients affected by COVID-19 had protection against risk of disease severity, complications (ES 0.80; 95% CI) and mortality (ES 0.69; 95% CI). Conclusions More in-depth studies on the use of metformin, compared to other molecules, may be required to understand the real protective potential of the drug against negative outcomes caused by COVID-19 infection in DM2 patients

    Hadronic Annihilation Decay Rates of P-wave Heavy Quarkonia with Both Relativistic and QCD Radiative Corrections

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    Hadronic annihilation decay rates of P-wave heavy quarkonia are given to next-to-leading order in both αs\alpha_s and v2v^2. They include ten nonperturbative parameters, which can be rigorously defined as the matrix elements of color-singlet and color-octet operators in NRQCD. We expect these papameters will be determined from lattice calculations in future.Comment: 5 Pages RevTex. The paper is withdraw

    Audio-based narratives for the trenches of World War I : intertwining stories, places and interaction for an evocative experience

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    We report in detail the co-design, setup and evaluation of a technological intervention for a complex outdoor heritage site: a World War I fortified camp and trenches located in the natural setting of the Italian Alps. Sound was used as the only means of content delivery as it was considered particularly effective in engaging visitors at an emotional level and had the potential to enhance the physical experience of being at an historical place. The implemented prototype is visitor-aware personalised multi-point auditory narrative system that automatically plays sounds and stories depending on a combination of features such as physical location, visitor proximity and visitor preferences. The curators created for the trail multiple narratives to capture the different voices of the War. The stories are all personal accounts (as opposed to objective and detached reporting of the facts); they were designed to trigger empathy and understanding while leaving the visitors free to interpret the content and the place on the bases of their own understanding and sensitivity. The result is an evocative embodied experience that does not describe the place in a traditional sense, but leaves its interpretation open. It takes visitors beyond the traditional view of heritage as a source of information toward a sensorial experience of feeling the past. A prototype was set up and tested with a group of volunteers showing that a design that carefully combines content design, sound design, tangible and embodied interaction can bring archaeological remains, with very little to see, back to file

    Report of the QCD Tools Working Group

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    We report on the activities of the ``QCD Tools for heavy flavors and new physics searches'' working group of the Run II Workshop on QCD and Weak Bosons. The contributions cover the topics of improved parton showering and comparisons of Monte Carlo programs and resummation calculations, recent developments in Pythia, the methodology of measuring backgrounds to new physics searches, variable flavor number schemes for heavy quark electro-production, the underlying event in hard scattering processes, and the Monte Carlo MCFM for NLO processes.Comment: LaTeX, 47 pages, 41 figures, 10 tables, uses run2col.sty, to appear in the Proceedings of the Workshop on "QCD and Weak Boson Physics in Run II", Fermilab, March - November 199

    Resummation of QCD Corrections to the eta_c Decay Rate

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    We examine the ratio of the decay rate of the eta_c into light hadrons to the decay rate into photons and find that most of the large next-to-leading-order (NLO) correction is associated with running of the strong coupling alpha_s. We resum such contributions by analyzing final-state chains of vacuum-polarization bubbles. We show that the nonperturbative parts of the bubble chains can be absorbed into a color-octet matrix element, once one has used contour deformations of the phase-space integrals to cancel certain contributions. We argue that these contributions are incompatible with the uncertainty principle. We also argue that perturbation theory is reliable only if one carries out the phase-space integrations before the perturbation summation. Our results are in good agreement with experiment and differ considerably from those that one obtains by applying the scale-setting method of Brodsky, Lepage, and Mackenzie to the NLO result.Comment: 41 pages, REVTEX, corrected minor typos in tex
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