Tight asymptotic key rate for the BB84 protocol with local randomisation and device imprecisions

Local randomisation is a preprocessing procedure in which one of the legitimate parties of a quantum key distribution (QKD) scheme adds noise to their version of the key and was found by Kraus et al. [Phys. Rev. Lett. 95, 080501 (2005)] to improve the security of certain QKD protocols. In this article, the improvement yielded by local randomisation is derived for an imperfect implementation of the BB84 QKD protocol, in which the source emits four given but arbitrary pure states and the detector performs arbitrarily-aligned measurements. Specifically, this is achieved by modifying an approach to analysing the security of imperfect variants of the BB84 protocol against collective attacks, introduced in [Phys. Rev. A 88, 012331 (2013)], to include the additional preprocessing step. The previously known improvement to the threshold channel noise, from 11\% to 12.41\%, is recovered in the special case of an ideal BB84 implementation and becomes more pronounced in the case of a nonideal source. Finally, the bound derived for the asymptotic key rate, both with and without local randomisation, is shown to be tight with the particular source characterisation used. This is demonstrated by the explicit construction of a family of source states and optimal attacks for which the key-rate bound is attained with equality

In search of the rainbow: pathways to quality in large scale programmes for young disadvantaged children

Development experts have searched for universal definitions and standards of quality. But quality is contextual. Using examples from several countries, this book argues that sensitivity to diversity and to one's own preconceptions should be key elements informing all early childhood work

Changing perspectives on early childhood: theory, research and policy

Early childhood policies and practices are shaped by competing images and discourses of the young child. This paper reviews four core perspectives that have been most influential. 1. A developmental perspective emphasizes regularities in young children’s physical and psychosocial growth during early childhood, as well as their dependencies and vulnerabilities during this formative, phase of their lives. 2. A political and economic perspective is informed by developmental principles, translated into social and educational interventions, and underpinned by economic models of human capital. 3. A social and cultural perspective draws attention to respects in which early childhood is a constructed status and to the diversities of ways it is understood and practised, for, with and by young children, with implications for how goals, models and standards are defined, and by whom. 4. A human rights perspective reframes conventional approaches to theory, research policy and practice in ways that fully respect young children’s dignity, their entitlements and their capacities to contribute to their own development and to the development of services. For each of these overarching perspectives, the paper outlines a cluster of specific theoretical, research and policy themes, summarizes major areas of controversy, and identifies a range of alternative visions for early childhood

The Children’s Perspectives Protocol: A participatory approach to studying child work issues

This is the summary of a research protocol constructed as part of the Radda Barnen project "Children’s perspectives on their working lives", originally published in 1998. It provided the framework for local investigators carrying-out the initial study with 50 groups of working children in diverse occupations in Bangladesh, Ethiopia, The Philippines and Central America. • The protocol was designed to inform popular assumptions about the impact of work in children's lives with evidence on children's own perception of their situation; • The protocol is applied in ways sensitive to the local circumstances of working children, and their preferred ways of communicating their experiences; • The protocol can be adapted to provide systematic, detailed accounts of specific occupational situations in ways that can inform context-appropriate interventions

Pathways through early childhood education in Ethiopia, India and Peru: Rights, equity and diversity. Young Lives Working Paper 54

The potential of quality early childhood and primary education to help break inter-generational poverty cycles is widely recognised. My focus is on how far this potential is being translated into reality, through implementing positive early childhood policies in practice. The paper summarises evidence from Young Lives research into early transitions, based on both survey and in-depth qualitative research with 2,000 Young Lives younger cohort children in Ethiopia, Andhra Pradesh (India) and Peru. Primary education is still being consolidated in Ethiopia, and pre-school is a minority urban experience, mainly offered by the private sector. Peru offers a very different story, with a well-established government primary and pre-school system but concerns about quality and coordination between sectors. Andhra Pradesh offers the most complex set of challenges, with a long-established government system of ECCE, but an increasing trend towards use of private services, including amongst the poorest communities. The paper offers five broad conclusions, about the importance of: ensuring quality and equity in early education; better coordinated pre-school and school systems; targeting the most vulnerable and disadvantaged children; recognising the full range of equity issues; and ensuring more effective governance, including governance of the private sector

Is there a place for work in child development? Implications of child development theory and research for interpretation of the UN Convention on the Rights of the Child, with particular reference to Article 32, on children, work and exploitation

This paper is about the role of child-development knowledge and research in international efforts to improve the lives and prospects for millions of working children. Article 32 of the UN Convention on the Rights of the Child is framed in psychological terms. It declares that children must be protected from work that is harmful to their ’physical, mental, spiritual, moral or social development’. The Convention presumes a universal concept of ’development’ and ’harm’ (in terms of what is healthy, natural or adjusted and in terms of adverse effects of work). Most textbooks of child development appear to confirm beliefs about universal, natural features of child development. But our knowledge about the abilities, needs and interests of children during successive stages of their lives is based on highly specific (mainly Euro-American) cultural contexts for childhood and goals for development. There is little space for work within this view of child development. This paper presents the case for a sociocultural approach to child development, as a more globally appropriate basis for evaluating the place of work in children’s lives. The concept of ’developmental niche’ is offered as a starting-point for understanding the place of work and evaluating its positive and negative effects in specific contexts. Relinquishing universal child-development knowledge sets new challenges for policy and for research. In the long term it has the potential to inform the implementation of UN Convention principles in context-appropriate and child-sensitive ways

Early Childhood Development in the SDGs

Agreement on the Sustainable Development Goals signals that early childhood development (ECD) will be a priority focus for the twenty-first century. Explicit mention is made in Target 4.2 which states that by 2030 countries should: ‘ensure that all girls and boys have access to quality early childhood development, care and pre-primary education so that they are ready for primary education’. But SDG commitments to ECD are much broader than this education- focused target. This Policy Brief offers five key messages that can underpin delivery of the SDGs through the transformative potential of accessible, inclusive, quality ECD – for all young girls and boys, and for their families