6,613 research outputs found

    Inelastic X-ray scattering from valence electrons near absorption edges of FeTe and TiSe2_2

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    We study resonant inelastic x-ray scattering (RIXS) peaks corresponding to low energy particle-hole excited states of metallic FeTe and semi-metallic TiSe2_2 for photon incident energy tuned near the L3L_{3} absorption edge of Fe and Ti respectively. We show that the cross section amplitudes are well described within a renormalization group theory where the effect of the core electrons is captured by effective dielectric functions expressed in terms of the the atomic scattering parameters f1f_1 of Fe and Ti. This method can be used to extract the dynamical structure factor from experimental RIXS spectra in metallic systems.Comment: 6 pages, 4 figure

    Thermodynamic equilibrium and its stability for Microcanonical systems described by the Sharma-Taneja-Mittal entropy

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    It is generally assumed that the thermodynamic stability of equilibrium state is reflected by the concavity of entropy. We inquire, in the microcanonical picture, on the validity of this statement for systems described by the bi-parametric entropy Sκ,rS_{_{\kappa, r}} of Sharma-Taneja-Mittal. We analyze the ``composability'' rule for two statistically independent systems, A and B, described by the entropy Sκ,rS_{_{\kappa, r}} with the same set of the deformed parameters. It is shown that, in spite of the concavity of the entropy, the ``composability'' rule modifies the thermodynamic stability conditions of the equilibrium state. Depending on the values assumed by the deformed parameters, when the relation Sκ,r(AB)>Sκ,r(A)+Sκ,r(B)S_{_{\kappa, r}}({\rm A}\cup{\rm B})> S_{_{\kappa, r}}({\rm A})+S_{_{\kappa, r}}({\rm B}) holds (super-additive systems), the concavity conditions does imply the thermodynamics stability. Otherwise, when the relation Sκ,r(AB)<Sκ,r(A)+Sκ,r(B)S_{_{\kappa, r}}({\rm A}\cup{\rm B})<S_{_{\kappa, r}}({\rm A})+S_{_{\kappa, r}}({\rm B}) holds (sub-additive systems), the concavity conditions does not imply the thermodynamical stability of the equilibrium state.Comment: 13 pages, two columns, 1 figure, RevTex4, version accepted on PR

    Equally attending but still not seeing : an eye-tracking study of change detection in own- and other-race faces

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    The present study aimed to investigate whether the faster change detection in own race faces in a change blindness paradigm, reported by Humphreys, Hodsoll and Campbell (2005, Visual Cognition, 12, 249-262) and explained in terms of people’s poorer ability to discriminate other race faces, may be explained by people’s preferential attention towards own race faces. The study by Humphreys et al. was replicated using the same stimuli, while participants’ eye movements were recorded. These revealed that there was no attentional bias towards own race faces (analysed in terms of fixation order, number and duration), but people still detected changes in own race faces faster than in other race faces. The current results therefore give further support for the original claim that people are less sensitive to changes made in other race faces, when own and other race faces are equally attended

    Positron Emission Tomography Score Has Greater Prognostic Significance Than Pretreatment Risk Stratification in Early-Stage Hodgkin Lymphoma in the UK RAPID Study.

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    PURPOSE: Accurate stratification of patients is an important goal in Hodgkin lymphoma (HL), but the role of pretreatment clinical risk stratification in the context of positron emission tomography (PET) -adapted treatment is unclear. We performed a subsidiary analysis of the RAPID trial to assess the prognostic value of pretreatment risk factors and PET score in determining outcomes. PATIENTS AND METHODS: Patients with stage IA to IIA HL and no mediastinal bulk underwent PET assessment after three cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine; 143 PET-positive patients (PET score, 3 to 5) received a fourth doxorubicin, bleomycin, vinblastine, and dacarbazine cycle and involved-field radiotherapy, and 419 patients in complete metabolic remission were randomly assigned to receive involved-field radiotherapy (n = 208) or no additional treatment (n = 211). Cox regression was used to investigate the association between PET score and pretreatment risk factors with HL-specific event-free survival (EFS). RESULTS: High PET score was associated with inferior EFS, before (P .4). CONCLUSION: In RAPID, a positive PET scan did not carry uniform prognostic weight; only a PET score of 5 was associated with inferior outcomes. This suggests that in future trials involving patients without B symptoms or mediastinal bulk, a score of 5 rather than a positive PET result should be used to guide treatment escalation in early-stage HL

    Project-based pedagogy in interdisciplinary building design adopting BIM

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    Purpose – This study aims to present a pedagogical practice in the project-based assessment of AEC students’ interdisciplinary building design work adopting BIM. This pedagogical practice emphasizes the impacts of BIM, as the digital collaboration platform, on the cross-disciplinary teamwork design through information sharing. This study also focuses on collecting students’ perceptions of BIM effects in integrated project design. Challenges in BIM adoption from AEC students’ perspective were identified and discussed, and could spark further research needs. Design/Methodology/Approach – Based on a thorough review of previous pedagogical practices of applying BIM in multiple AEC disciplines, this study adopted a case study of the Solar Decathlon residential building design as the group project for AEC students to deliver the design work and construction planning. In total 13 different teams within the University of Nottingham Ningbo China, each group consisting of final year undergraduate students with backgrounds in architecture, civil engineering, and architectural environmental engineering, worked to deliver the detailed design of the solar-powered residential house meeting pre-specified project objectives in terms of architectural aesthetics, structural integrity, energy efficiency, prefabrication construction techniques, and other issues such as budget and scheduling. Each team presented the cross-disciplinary design plan with cost estimate and construction scheduling together with group reports. This pedagogical study collected students’ reflective thinking on how BIM affected their design work, and compared their feedback on BIM to that from AEC industry professionals in previous studies. Findings – The case study of the Solar Decathlon building project showed the capacity of BIM in enabling interdisciplinary collaboration through information exchange and in enhancing communication across different AEC fields. More sustainable design options were considered in the early architectural design stages through the cross-disciplinary cooperation between architecture and building services engineering. BIM motivated AEC student teams to have a more comprehensive design and construction plan by considering multiple criteria including energy efficiency, budget, and construction activities. Students’ reflections indicated both positive effects of BIM (e.g., facilitating information sharing) as well as challenges for further BIM implementation, such as some architecture students’ resistance to BIM, and the lack of existing family types in the BIM library, etc. Research limitations/implications – Some limitations of the current BIM pedagogy were identified through the student group work. For example, students revealed the problem of interoperability between BIM (i.e., Autodesk Revit) and building energy simulation tools. To further integrate the university education and AEC industry practice, future BIM pedagogical work could recruit professionals and project stakeholders in the adopted case studies, for the purpose of providing professional advice on improving the constructability of the BIM-based design from student work. Originality/value – This work provides insights into the information technology applied in the AEC interdisciplinary pedagogy. Students gained the experience of a project-based collaboration and were equipped with BIM capabilities for future employment within the AEC job market. The integrated design approach was embedded throughout the team project process. Overall, this BIM pedagogical practice emphasized the link between academic activities and real-world industrial practice. The pedagogical experience gained in this BIM course could be expanded to future BIM education and research in other themes such as interoperability of building information exchange among different digital tools

    Quantum Mechanics Another Way

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    Deformation quantization (sometimes called phase-space quantization) is a formulation of quantum mechanics that is not usually taught to undergraduates. It is formally quite similar to classical mechanics: ordinary functions on phase space take the place of operators, but the functions are multiplied in an exotic way, using the star product. Here we attempt a brief, pedagogical discussion of deformation quantization, that is suitable for inclusion in an undergraduate course.Comment: 14 pages, 3 figures, to be published in Eur. J. Phy

    Unraveling the Nature of Charge Excitations in La2_2CuO4_4 with Momentum-Resolved Cu KK-edge Resonant Inelastic X-ray Scattering

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    Results of model calculations using exact diagonalization reveal the orbital character of states associated with different Raman loss peaks in Cu KK-edge resonant inelastic X-ray scattering (RIXS) from La2_{2}CuO4_{4}. The model includes electronic orbitals necessary to highlight non-local Zhang-Rice singlet, charge transfer and dd-dd excitations, as well as states with apical oxygen 2pzp_z character. The dispersion of these excitations is discussed with prospects for resonant final state wave-function mapping. A good agreement with experiments emphasizes the substantial multi-orbital character of RIXS profiles in the energy transfer range 1-6 eV.Comment: Original: 4.5 pages. Replaced: 4 pages and 4 figures with updated content and reference

    The Spitzer Spirals, Bridges, and Tails Interacting Galaxy Survey: Interaction-Induced Star Formation in the Mid-Infrared

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    We present Spitzer mid-infrared imaging of a sample of 35 tidally-distorted pre-merger interacting galaxy pairs selected from the Arp Atlas. We compare their global mid-infrared properties with those of normal galaxies from the SINGS Spitzer Legacy survey, and separate the disk emission from that of the tidal features. The [8.0 micron] - [24 micron], [3.6 micron] - [24 micron], and [5.8 micron] - [8.0 micron] colors of these optically-selected interacting galaxies are redder on average than those of spirals, implying enhancements to the mass-normalized star formation rates (SFRs) of a factor of ~2. Furthermore, the 24 micron emission in the Arp galaxies is more centrally concentrated than that in the spirals, suggesting that gas is being concentrated into the inner regions and fueling central star formation. No significant differences can be discerned in the shorter wavelength Spitzer colors of the Arp galaxies compared to the spirals, thus these quantities are less sensitive to star formation enhancements. No strong trend of Spitzer color with pair separation is visible in our sample; this may be because our sample was selected to be tidally disturbed. The tidal features contribute <10% of the total Spitzer fluxes on average. The SFRs implied for the Arp galaxies by the Spitzer 24 micron luminosities are relatively modest, ~1 M(sun)/yr on average

    Who is to blame? The relationship between ingroup identification and relative deprivation is moderated by ingroup attributions

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    Contradictory evidence can be found in the literature about whether ingroup identification and perceived relative deprivation are positively or negatively related. Indeed, theoretical arguments can be made for both effects. It was proposed that the contradictory findings can be explained by considering a hitherto unstudied moderator: The extent to which deprivation is attributed to the ingroup. It was hypothesised that identification would only have a negative impact on deprivation, and that deprivation would only have a negative impact on identification, if ingroup attributions are high. To test this, attributions to the ingroup were experimentally manipulated among British student participants (N = 189) who were asked about their perceived deprivation vis-à-vis German students, yield ing support for the hypotheses

    Predicting uncertainty in sediment transport and landscape evolution - the influence of initial surface conditions

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    © 2015. Numerical landscape evolution models were initially developed to examine natural catchment hydrology and geomorphology and have become a common tool to examine geomorphic behaviour over a range of time and space scales. These models all use a digital elevation model (DEM) as a representation of the landscape surface and a significant issue is the quality and resolution of this surface. Here we focus on how subtle perturbations or roughness on the DEM surface can produce alternative model results. This study is carried out by randomly varying the elevations of the DEM surface and examining the effect on sediment transport rates and geomorphology for a proposed rehabilitation design for a post-mining landscape using multiple landscape realisations with increasing magnitudes of random changes. We show that an increasing magnitude of random surface variability does not appear to have any significant effect on sediment transport over millennial time scales. However, the random surface variability greatly changes the temporal pattern or delivery of sediment output. A significant finding is that all simulations at the end of the 10,000 year modelled period are geomorphologically similar and present a geomorphological equifinality. However, the individual patterns of erosion and deposition were different for repeat simulations with a different sequence of random perturbations. The alternative positions of random perturbations strongly influence local patterns of hillslope erosion and evolution together with the pattern and behaviour of deposition. The findings demonstrate the complex feedbacks that occur even within a simple modelled system
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