266 research outputs found

    Quantum phase transitions in alternating spin-(1/2, 5/2) Heisenberg chains

    Full text link
    The ground state spin-wave excitations and thermodynamic properties of two types of ferrimagnetic chains are investigated: the alternating spin-1/2 spin-5/2 chain and a similar chain with a spin-1/2 pendant attached to the spin-5/2 site. Results for magnetic susceptibility, magnetization and specific heat are obtained through the finite-temperature Lanczos method with the aim in describing available experimental data, as well as comparison with theoretical results from the semiclassical approximation and the low-temperature susceptibility expansion derived from Takahashi's modified spin-wave theory. In particular, we study in detail the temperature vs. magnetic field phase diagram of the spin-1/2 spin-5/2 chain, in which several low-temperature quantum phases are identified: the Luttinger Liquid phase, the ferrimagnetic plateau and the fully polarized one, and the respective quantum critical points and crossover lines

    Data-Driven Analysis of Engagement in Gamified Learning Environments: A Methodology for Real-Time Measurement of MOOCs

    Get PDF
    Welfare and economic development is directly dependent on the availability of highly skilled and educated individuals in society. In the UK, higher education is accessed by a large percentage of high school graduates (50% in 2017). Still, in Brazil, a limited number of pupils leaving high schools continue their education (up to 20%). Initial pioneering efforts of universities and companies to support pupils from underprivileged backgrounds, to be able to succeed in being accepted by universities include personalised learning solutions. However, initial findings show that typical distance learning problems occur with the pupil population: isolation, demotivation, and lack of engagement. Thus, researchers and companies proposed gamification. However, gamification design is traditionally exclusively based on theory-driven approaches and usually ignore the data itself. This paper takes a different approach, presenting a large-scale study that analysed, statistically and via machine learning (deep and shallow), the first batch of students trained with a Brazilian gamified intelligent learning software (called CamaleOn), to establish, via a grassroots method based on learning analytics, how gamification elements impact on student engagement. The exercise results in a novel proposal for real-time measurement on Massive Open Online Courses (MOOCs), potentially leading to iterative improvements of student support. It also specifically analyses the engagement patterns of an underserved community

    Integration between Primary Health Care and Emergency Services in Brazil: Barriers and Facilitators

    Get PDF
    Introduction: Characteristics of primary health care and emergency services may hamper their integration and, therefore, reduce the quality of care and the effectiveness of health systems. This study aims to identify and analyse policy, structural and organizational aspects of healthcare services that may affect the integration between primary health and emergency care networks. Theory and Methods: We conducted a qualitative research study based on grounded theory that included: (1) interviews with 30 health care leaders; and (2) documental analysis of the summaries of Regional Interagency Committee meetings from two regions in the state of Sao Paulo, Brazil. Results: The integration between primary health and emergency care network is inefficient. The barriers that contributed to this situation are as follows: (1) policy: the municipal health department is responsible for providing primary health care and the regional health department provides emergency care, but there is a lack of space for the integration of services; (2) structural: distinct criteria for planning mechanisms; and (3) organizational: ineffective point of interaction between different levels of the health system. Conclusions and discussion: Our findings have implications for health management and planning in low-and middle-income countries (LMICs) with suggestions for interventions for overcoming the aforementioned barriers

    Gerenciamento genético da tilápia nos cultivos comerciais.

    Get PDF
    Introdução. Desafios da produção. Manejo sanitário de peixes. Situação da distribuição de alevinos no Brasil. Gerenciamento das fases jovens nas pisciculturas comerciais. Exemplo do gerenciamento genético da Tilápia em outros países. Tendências e oportunidades. Considerações finais. Referências.bitstream/item/139186/1/CNPASA-2015-doc23.pd

    Prenatal Hypoxic-Ischemic Insult Changes the Distribution and Number of NADPH-Diaphorase Cells in the Cerebellum

    Get PDF
    Astrogliosis, oligodendroglial death and motor deficits have been observed in the offspring of female rats that had their uterine arteries clamped at the 18th gestational day. Since nitric oxide has important roles in several inflammatory and developmental events, here we evaluated NADPH-diaphorase (NADPH-d) distribution in the cerebellum of rats submitted to this hypoxia-ischemia (HI) model. At postnatal (P) day 9, Purkinje cells of SHAM and non-manipulated (NM) animals showed NADPH-d+ labeling both in the cell body and dendritic arborization in folia 1 to 8, while HI animals presented a weaker labeling in both cellular structures. NADPH-d+ labeling in the molecular (ML), and in both the external and internal granular layer, was unaffected by HI at this age. At P23, labeling in Purkinje cells was absent in all three groups. Ectopic NADPH-d+ cells in the ML of folia 1 to 4 and folium 10 were present exclusively in HI animals. This labeling pattern was maintained up to P90 in folium 10. In the cerebellar white matter (WM), at P9 and P23, microglial (ED1+) NADPH-d+ cells, were observed in all groups. At P23, only HI animals presented NADPH-d labeling in the cell body and processes of reactive astrocytes (GFAP+). At P9 and P23, the number of NADPH-d+ cells in the WM was higher in HI animals than in SHAM and NM ones. At P45 and at P90 no NADPH-d+ cells were observed in the WM of the three groups. Our results indicate that HI insults lead to long-lasting alterations in nitric oxide synthase expression in the cerebellum. Such alterations in cerebellar differentiation might explain, at least in part, the motor deficits that are commonly observed in this model
    corecore