563 research outputs found

    Raman spectroscopy study of the interface structure in (CaCuO2)n/(SrTiO3)m superlattices

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    Raman spectra of CaCuO2/SrTiO3 superlattices show clear spectroscopic marker of two structures formed in CaCuO2 at the interface with SrTiO3. For non-superconducting superlattices, grown in low oxidizing atmosphere, the 425 cm-1 frequency of oxygen vibration in CuO2 planes is the same as for CCO films with infinite layer structure (planar Cu-O coordination). For superconducting superlattices grown in highly oxidizing atmosphere, a 60 cm-1 frequency shift to lower energy occurs. This is ascribed to a change from planar to pyramidal Cu-O coordination because of oxygen incorporation at the interface. Raman spectroscopy proves to be a powerful tool for interface structure investigation

    Coexistence of pressure-induced structural phases in bulk black phosphorus: a combined x-ray diffraction and Raman study up to 18 GPa

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    We report a study of the structural phase transitions induced by pressure in bulk black phosphorus by using both synchrotron x-ray diffraction for pressures up to 12.2 GPa and Raman spectroscopy up to 18.2 GPa. Very recently black phosphorus attracted large attention because of the unique properties of fewlayers samples (phosphorene), but some basic questions are still open in the case of the bulk system. As concerning the presence of a Raman spectrum above 10 GPa, which should not be observed in an elemental simple cubic system, we propose a new explanation by attributing a key role to the non-hydrostatic conditions occurring in Raman experiments. Finally, a combined analysis of Raman and XRD data allowed us to obtain quantitative information on presence and extent of coexistences between different structural phases from ~5 up to ~15 GPa. This information can have an important role in theoretical studies on pressure-induced structural and electronic phase transitions in black phosphorus

    A PC-Based Instrument for Automatic Monitoring and Control of a CPVT Power Plant

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    A PC-based instrument has been developed for the monitoring and control of a concentrated photovoltaic and thermal (CPVT) power plant. The instrument allows acquiring both electrical and thermal quantities. Moreover it implements the solar tracking algorithm used to optimize the power production

    Does Learning Through Movement Improve Academic Performance in Primary Schoolchildren? A Systematic Review

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    Physically active children have greater motor competence and a faster maturation compared with their sedentary peers. Recent research also suggests that physical activity during childhood may also promote cognitive development and therefore improve academic performance. The aim of this study was to understand if physically active academic lessons may improve academic achievement in primary schoolchildren. A systematic review following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was conducted. The search was performed on the following database: PubMed, Web of Science, Scopus, Education Resources Information Center (ERIC), and PsycINFO (APA). Studies evaluating schoolchildren aged between 3 and 11 years taking part in educational contexts that include physical activity and natural environments evaluating physical fitness and/or educational outcomes were included. A total of 54 studies (for a total sample of 29,460 schoolchildren) were considered eligible and included in the qualitative synthesis. The Effective Public Health Practice Project risk-of-bias assessment revealed a moderate quality of the included studies with only two considered weeks. Despite differences in the retrieved protocols, physically active academic lessons improve the total time engaged in physical activity, motor skills, and/or academic performance. The results of this review suggest that learning through movement is an effective, low-cost, and enjoyable strategy for elementary schoolchildren

    The Gaia-ESO Survey: membership and Initial Mass Function of the Gamma Velorum cluster

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    Understanding the properties of young open clusters, such as the Initial Mass Function (IMF), star formation history and dynamic evolution, is crucial to obtain reliable theoretical predictions of the mechanisms involved in the star formation process. We want to obtain a list, as complete as possible, of confirmed members of the young open cluster Gamma Velorum, with the aim of deriving general cluster properties such as the IMF. We used all available spectroscopic membership indicators within the Gaia-ESO public archive together with literature photometry and X-ray data and, for each method, we derived the most complete list of candidate cluster members. Then, we considered photometry, gravity and radial velocities as necessary conditions to select a subsample of candidates whose membership was confirmed by using the lithium and Hα\alpha lines and X-rays as youth indicators. We found 242 confirmed and 4 possible cluster members for which we derived masses using very recent stellar evolutionary models. The cluster IMF in the mass range investigated in this study shows a slope of α=2.6±0.5\alpha=2.6\pm0.5 for 0.5<M/M⊙<1.30.5<M/M_\odot <1.3 and α=1.1±0.4\alpha=1.1\pm0.4 for 0.16<M/M⊙<0.50.16<M/M_\odot <0.5 and is consistent with a standard IMF. The similarity of the IMF of the young population around γ2\gamma^2 Vel to that in other star forming regions and the field suggests it may have formed through very similar processes.Comment: Accepted for publication in A&A; 18 pages, 11 figures, 5 table

    Issues and challenges in the application of Husserlian phenomenology to the Lived Experience of Hate Crime and Its Legal Aftermath

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    The field of hate crime research addresses the presence, sources and impact of particular types of expressions of prejudice, often perceived as particularly damaging and hurtful forms of interpersonal abuse and violence. Little, if any, credible academic research seeks to vindicate the specific racist, gendered and other vicious prejudices articulated by many perpetrators of hate crime. In turn, this raises the reflexive question of the possibilities of researchers themselves ever being able to adopt a truly "unprejudiced" approach to the presence of such damaging prejudices. Can this goal be realised without a researcher necessarily losing an experientially-grounded understanding of what these meanings, values and purposes have come to mean, and how they are themselves interpretatively re-constituted anew, including within the lived experience of victims, witnesses, police, prosecutors, judges and victim support workers? A possible philosophically-informed approach to the dilemmas posed by this topic is offered by Husserl's phenomenology. Husserl's perpetually unfinished philosophical methodology strives, with concerted if sometimes tragic reflective rigor, to "suspend," "bracket out" and "neutralise" those core presuppositions constitutive of the research field that typically pre-judge precisely whatever demands to be questioned and explored in a radically non-prejudicial manner. This study critically explores the possibilities, reflective stages and theoretical limitations of a sympathetically reconstructed Husserlian approach to hate crime, itself understood as a would-be qualitative "science of consciousness." It argues that despite its manifest tensions, gaps, ambiguities and internal contradictions, aspects of the Husserlian philosophical approach directed towards the different levels of experienced hate crime still retain the potential to both challenge and advance our understanding of this topic. It is the "instructive" part of "instructive failure" that this article highlights

    On staying grounded and avoiding Quixotic dead ends

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    The 15 articles in this special issue on The Representation of Concepts illustrate the rich variety of theoretical positions and supporting research that characterize the area. Although much agreement exists among contributors, much disagreement exists as well, especially about the roles of grounding and abstraction in conceptual processing. I first review theoretical approaches raised in these articles that I believe are Quixotic dead ends, namely, approaches that are principled and inspired but likely to fail. In the process, I review various theories of amodal symbols, their distortions of grounded theories, and fallacies in the evidence used to support them. Incorporating further contributions across articles, I then sketch a theoretical approach that I believe is likely to be successful, which includes grounding, abstraction, flexibility, explaining classic conceptual phenomena, and making contact with real-world situations. This account further proposes that (1) a key element of grounding is neural reuse, (2) abstraction takes the forms of multimodal compression, distilled abstraction, and distributed linguistic representation (but not amodal symbols), and (3) flexible context-dependent representations are a hallmark of conceptual processing
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