1,071 research outputs found

    Heavily reddened type 1 quasars at z > 2 I: Evidence for significant obscured black-hole growth at the highest quasar luminosities

    Full text link
    We present a new population of z>2 dust-reddened, Type 1 quasars with 0.5<E(B-V)<1.5, selected using near infra-red (NIR) imaging data from the UKIDSS-LAS, ESO-VHS and WISE surveys. NIR spectra obtained using the Very Large Telescope (VLT) for 24 new objects bring our total sample of spectroscopically confirmed hyperluminous (>10^{13}L_0), high-redshift dusty quasars to 38. There is no evidence for reddened quasars having significantly different Hα\alpha equivalent widths relative to unobscured quasars. The average black-hole masses (~10^9-10^10 M_0) and bolometric luminosities (~10^{47} erg/s) are comparable to the most luminous unobscured quasars at the same redshift, but with a tail extending to very high luminosities of ~10^{48} erg/s. Sixty-six per cent of the reddened quasars are detected at >3σ>3\sigma at 22um by WISE. The average 6um rest-frame luminosity is log10(L6um/erg/s)=47.1+/-0.4, making the objects among the mid-infrared brightest AGN currently known. The extinction-corrected space-density estimate now extends over three magnitudes (-30 < M_i < -27) and demonstrates that the reddened quasar luminosity function is significantly flatter than that of the unobscured quasar population at z=2-3. At the brightest magnitudes, M_i < -29, the space density of our dust-reddened population exceeds that of unobscured quasars. A model where the probability that a quasar becomes dust-reddened increases at high luminosity is consistent with the observations and such a dependence could be explained by an increase in luminosity and extinction during AGN-fuelling phases. The properties of our obscured Type 1 quasars are distinct from the heavily obscured, Compton-thick AGN that have been identified at much fainter luminosities and we conclude that they likely correspond to a brief evolutionary phase in massive galaxy formation.Comment: 16 pages, 9 figures (+ 2 appendices), Accepted for publication in MNRA

    Two 'transitions': the political economy of Joyce Banda's rise to power and the related role of civil society organisations in Malawi

    Get PDF
    This is an Accepted Manuscript of an article published by Taylor & Francis in Review of African Political Economy on 21/07/2014, available online: http://www.tandfonline.com/doi/abs/10.1080/03056244.2014.90194

    Money talks: moral economies of earning a living in neoliberal East Africa

    Get PDF
    Neoliberal restructuring has targeted not just the economy, but also polity, society and culture, in the name of creating capitalist market societies. The societal repercussions of neoliberal policy and reform in terms of moral economy remain understudied. This article seeks to address this gap by analysing moral economy characteristics and dynamics in neoliberalised communities, as perceived by traders in Uganda and sex workers in Kenya. The interview data reveal perceived drivers that contributed to a significant moral dominance of money, self-interest, short-termism, opportunism and pragmatism. Equally notable are a perceived (i) close interaction between political–economic and moral–economic dynamics, and (ii) significant impact of the political–economic structure on moral agency. Respondents primarily referred to material factors usually closely linked to neoliberal reform, as key drivers of local moral economies. We thus speak of a neoliberalisation of moral economies, itself part of the wider process of embedding and locking-in market society structures in the two countries. An improved political economy of moral economy can help keep track of this phenomenon

    Perceptions of Earth Science using assistive and supportive technologies by students who are blind or visually impaired

    Get PDF
    Students with blindness or visual impairments (BVI) need to participate in scientific laboratory experiences at the K12 level to be successful in college-level science courses. These K12 level students need instruction to actively conduct science experiments and not only allow sighted students to conduct them. While it may be a challenge, with appropriate assistive and supportive technologies, students with BVI can be successful in conducting scientific investigations to address Next Generation Science Standards. The Discoveries in Earth Science (DES) program provides engaging accommodations adaptive to the needs of elementary, middle, and high school grade students with BVI to successfully prepare for careers in STEM

    Modelling the impact of women’s education on fertility in Malawi

    Get PDF
    Many studies have suggested that there is an inverse relationship between education and number of children among women from sub-Saharan Africa countries, including Malawi. However, a crucial limitation of these analyses is that they do not control for the potential endogeneity of education. The aim of our study is to estimate the role of women’s education on their number of children in Malawi, accounting for the possible presence of endogeneity and for nonlinear effects of continuous observed confounders. Our analysis is based on micro data from the 2010 Malawi Demographic Health Survey, and uses a flexible instrumental variable regression approach. The results suggest that the relationship of interest is affected by endogeneity and exhibits an inverted U-shape among women living in rural areas of Malawi, whereas it exhibits an inverse (nonlinear) relationship for women living in urban areas

    Health Expenditures and Health Outcomes in Kenya

    Get PDF
    Health inputs are critical in attaining a healthy nation and improving health outcomes. Kenya, like other developing countries, grapples with limited health expenditures and poor population health indicators. Specifically, Kenya is yet to achieve the allocation of least 15% of the government’s annual budget to improve the health sector as enshrined in the Abuja Declaration. Though there is an improvement with regards to infant mortality rate decreasing from 96.6 per 1, 000 live birth in 1970 to 30.6 per 1, 000 live birth in 2018. This indicator of population health outcome is currently far below the Sustainable Development Goals (SDGs) target of reducing the under five mortality rate to as low as 12 deaths per 1,000 live births by 2030. The literature suggests that increase in government’s budgetary allocation to the health sector can improve country’s health outcomes. Evidence on the impact of health expenditures on health outcomes is mixed and limited in developing countries. This study aims to analyze the impact of public health expenditures on health outcomes, among other control variables in Kenya. The study uses time series data from 1970 to 2018. The variables are found to be integrated of different orders suggesting the choice of Autoregressive Distributed Lag (ARDL) model. ARDL provides a useful link between long run equilibrium relationships and short run disequilibrium dynamics is estimated. The ARDL bounds test suggests presence of cointegration thus leading to the estimation of Error Correction Model (ECM). The findings suggest that improvements in public health expenditures enhance health outcomes in Kenya. The control variablesthat are found to be important determinants of infant mortality rate in Kenya include the national income and number of hospital beds per 100, 000. The study recommends that Kenyan government should increase annual budgetary allocation to health sector. Such increase is likely to lead to investments in physical and human capital in the health sector thus translating to improved health outcomes in Kenya

    Plant-mediated effects on mosquito capacity to transmit human malaria

    Get PDF
    The ecological context in which mosquitoes and malaria parasites interact has received little attention, compared to the genetic and molecular aspects of malaria transmission. Plant nectar and fruits are important for the nutritional ecology of malaria vectors, but how the natural diversity of plant-derived sugar sources affects mosquito competence for malaria parasites is unclear. To test this, we infected Anopheles coluzzi, an important African malaria vector, with sympatric field isolates of Plasmodium falciparum, using direct membrane feeding assays. Through a series of experiments, we then examined the effects of sugar meals from Thevetia neriifolia and Barleria lupilina cuttings that included flowers, and fruit from Lannea microcarpa and Mangifera indica on parasite and mosquito traits that are key for determining the intensity of malaria transmission. We found that the source of plant sugar meal differentially affected infection prevalence and intensity, the development duration of the parasites, as well as the survival and fecundity of the vector. These effects are likely the result of complex interactions between toxic secondary metabolites and the nutritional quality of the plant sugar source, as well as of host resource availability and parasite growth. Using an epidemiological model, we show that plant sugar source can be a significant driver of malaria transmission dynamics, with some plant species exhibiting either transmission-reducing or -enhancing activities
    corecore