Golden Opportunity or False Hope? Anglogold Ashanti's Proposed Gold Mine in the Democratic Republic of Congo

Deals with the exploitation of resourcesin DR

Using group therapy to support eating disordered mothers with their children: the relevance for primary care

Eating disorders are a crippling and disabling condition. If they become chronic, the emotional, physical and social effects are substantial. The death rate is the highest of all psychiatric illnesses so the need to find prevention strategies is urgent. This research project has three aims, primary prevention of an eating disorder for the child, helping the mother recover and developing a protocol for a group to be used in primary care. Children of mothers with an eating disorder, are a proven ‘at risk’ group, because children model and internalize their experiences. This project was carried out in a community setting, targeting mothers with an eating disorder who had children under the age of 13. It was argued that if these mothers can be encouraged to change the dysfunctional behaviour they may be passing on to their children, an attempt can be made to break the cycle. This qualitative research pilot project utilized semi-structured interviews before and after 11 weeks of group therapy, with three- and six-month follow-ups. Although the sample was small, the results showed that a group allowed these mothers a safe space for reflection, enabling them to become aware of their behaviour. As a result the mothers implemented changes in response to their children's needs, encouraging healthier development. The pilot was a precursor for a larger study to be carried out and developed within the primary care network

Proposed optical realisation of a two photon, four-qubit entangled χ\chi state

The four-qubit states $\lvert\chi^{ij}\rangle$, exhibiting genuinely multi-partite entanglement have been shown to have many interesting properties and have been suggested for novel applications in quantum information processing. In this work we propose a simple quantum circuit and its corresponding optical embodiment with which to prepare photon pairs in the $\lvert\chi^{ij}\rangle$ states. Our approach uses hyper-entangled photon pairs, produced by the type-I spontaneous parametric down-conversion (SPDC) process in two contiguous nonlinear crystals, together with a set of simple linear-optical transformations. Our photon pairs are maximally hyper-entangled in both their polarisation and orbital angular momentum (OAM). After one of these daughter photons passes through our optical setup, we obtain photon pairs in the hyper-entangled state $\lvert\chi^{00}\rangle$, and the $\lvert\chi^{ij}\rangle$ states can be achieved by further simple transformations.Comment: Submitted to Journal of Optic

Optimal discrimination of single-qubit mixed states

We consider the problem of minimum-error quantum state discrimination for single-qubit mixed states. We present a method which uses the Helstrom conditions constructively and analytically; this algebraic approach is complementary to existing geometric methods, and solves the problem for any number of arbitrary signal states with arbitrary prior probabilities.Comment: 8 pages, 1 figur

Gleason-Busch theorem for sequential measurements

Gleason's theorem is a statement that, given some reasonable assumptions, the Born rule used to calculate probabilities in quantum mechanics is essentially unique [A. M. Gleason, Indiana Univ. Math. J. 6, 885 (1957)]. We show that Gleason's theorem contains within it also the structure of sequential measurements, and along with this the state update rule. We give a small set of axioms, which are physically motivated and analogous to those in Busch's proof of Gleason's theorem [P. Busch, Phys. Rev. Lett. 91, 120403 (2003)], from which the familiar Kraus operator form follows. An axiomatic approach has practical relevance as well as fundamental interest, in making clear those assumptions which underlie the security of quantum communication protocols. Interestingly, the two-time formalism is seen to arise naturally in this approach

Optimal sequential measurements for bipartite state discrimination

State discrimination is a useful test problem with which to clarify the power and limitations of different classes of measurement. We consider the problem of discriminating between given states of a bipartite quantum system via sequential measurement of the subsystems, with classical feed-forward of measurement results. Our aim is to understand when sequential measurements, which are relatively easy to implement experimentally, perform as well, or almost as well, as optimal joint measurements, which are in general more technologically challenging. We construct conditions that the optimal sequential measurement must satisfy, analogous to the well-known Helstrom conditions for minimum error discrimination in the unrestricted case. We give several examples and compare the optimal probability of correctly identifying the state via global versus sequential measurement strategies

Is coherence catalytic?

Quantum coherence, the ability to control the phases in superposition states is a resource, and it is of crucial importance, therefore, to understand how it is consumed in use. It has been suggested that catalytic coherence is possible, that is repeated use of the coherence without degradation or reduction in performance. The claim has particular relevance for quantum thermodynamics because, were it true, it would allow free energy that is locked in coherence to be extracted $\textit{indefinitely}$. We address this issue directly with a careful analysis of the proposal by $\AA{}$berg. We find that coherence $\textit{cannot}$ be used catalytically, or even repeatedly without limit.Comment: 23 pages with 2 figure

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Regulating Human Germline Modification in Light of CRISPR

This comment evaluates the United States‘ current regulatory scheme as it applies to CRISPR and related gene-modifying technologies and discusses the ethical ramifications of regulating human germline modification versus continuing to allow self-regulation within the scientific community. Part I explains what CRISPR is, how it works, and its impact on genetic engineering technology. Although CRISPR offers unparalleled potential for modifying [both] human and nonhuman genomes, this comment focuses primarily on the use of CRISPR technology to manipulate the human germline. Part II discusses the social and bioethical implications of altering the human germline, including safety concerns, multigenerational consequences, equity issues, and ethical complications involved with editing human embryos. Part III examines the United States‘ current regulatory scheme as it applies to gene-modifying technologies, discusses the need for reform in light of CRISPR germline-editing therapies, looks at several possible solutions to improve the existing scheme, and proposes an adapted regulatory framework