221 research outputs found

    APRESENTAÇÃO

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    Temas centrais na historiografia africanista, o domínio político, a escravidão e o trabalho forçado são abordados nesse dossiê a partir da reação dos africanos ao modo como esses fenômenos ocorreram em Angola, Moçambique e no Congo. Os artigos resultam de apresentações realizadas durante o Seminário Internacional Cultura, Política e Trabalho na África Meridional, que teve lugar na Universidade Estadual de Campinas - UNICAMP (Brasil), entre 11 e 14 de maio de 2015, promovido pelo Centro de Pes..

    Evaluating the Performance of Ultra-Low-Field MRI for In-vivo 3D Current Density Imaging of the Human Head

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    Magnetic fields associated with currents flowing in tissue can be measured non-invasively by means of zero-field-encoded ultra-low-field magnetic resonance imaging (ULF MRI) enabling current density imaging (CDI) and possibly conductivity mapping of human head tissues. Since currents applied to a human are limited by safety regulations and only a small fraction of the current passes through the relatively high-resistive skull, a sufficient signal-to-noise ratio (SNR) may be difficult to obtain when using this method. In this work, we study the relationship between the image SNR and the SNR of the field reconstructions from zero-field-encoded data. We evaluate these results for two existing ULF MRI scanners, one ultra-sensitive single-channel system and one whole-head multi-channel system, by simulating sequences necessary for current-density reconstruction. We also derive realistic current-density and magnetic-field estimates from finite-element-method simulations based on a three-compartment head model. We found that existing ULF-MRI systems reach sufficient SNR to detect intra-cranial current distributions with statistical uncertainty below 10%. However, they also reveal that image artifacts influence the reconstruction quality. Further, our simulations indicate that current-density reconstruction in the scalp requires a resolution less than 5 mm and demonstrate that the necessary sensitivity coverage can be accomplished by multi-channel devices.Comment: 18 pages, 8 figures. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 68686

    Optical properties of silicon-implanted polycrystalline diamond membranes

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    We investigate the optical properties of polycrystalline diamond membranes containing silicon-vacancy (SiV) color centers in combination with other nano-analytical techniques. We analyze the correlation between the Raman signal, the SiV emission, and the background luminescence in the crystalline grains and in the grain boundaries, identifying conditions for the addressability of single SiV centers. Moreover, we perform a scanning transmission electron microscopy (STEM) analysis, which associates the microscopic structure of the membranes and the evolution of the diamond crystal along the growth direction with the photoluminescence properties, as well as a time-of-flight secondary ion mass spectrometry (ToF-SIMS) to address the distribution of silicon in implanted and un-implanted membranes. The results of the STEM and ToF-SIMS studies are consistent with the outcome of the optical measurements and provide useful insight into the preparation of polycrystalline samples for quantum nano-optics.Comment: 21 pages, 8 figure

    A Prospective Evaluation of Shared Decision-making Regarding Analgesics Selection for Older Emergency Department Patients With Acute Musculoskeletal Pain

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    Musculoskeletal pain is a common reason for emergency department (ED) visit by older adults. Outpatient pain management following ED visits in this population is challenging as a result of contraindications to, and side effects from, available therapies. Shared decision-making (SDM) between patients and emergency physicians may improve patient experiences and health outcomes. Among older ED patients with acute musculoskeletal pain, we sought to characterize their desire for involvement in the selection of outpatient analgesics. We also sought to assess the impact of SDM on change in pain at 1 week, patient satisfaction, and side effects
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