Compressed sensing and sparsity in photoacoustic tomography

Increasing the imaging speed is a central aim in photoacoustic tomography. This issue is especially important in the case of sequential scanning approaches as applied for most existing optical detection schemes. In this work we address this issue using techniques of compressed sensing. We demonstrate, that the number of measurements can significantly be reduced by allowing general linear measurements instead of point-wise pressure values. A main requirement in compressed sensing is the sparsity of the unknowns to be recovered. For that purpose, we develop the concept of sparsifying temporal transforms for three-dimensional photoacoustic tomography. We establish a two-stage algorithm that recovers the complete pressure signals in a first step and then apply a standard reconstruction algorithm such as back-projection. This yields a novel reconstruction method with much lower complexity than existing compressed sensing approaches for photoacoustic tomography. Reconstruction results for simulated and for experimental data verify that the proposed compressed sensing scheme allows for reducing the number of spatial measurements without reducing the spatial resolution.ope

Fracture mechanics description of the defect in rolling cylinder

project m- IPMinfra (CZ.02.1.01/0.0/0.0/16_013/0001823

Double quantum dot with integrated charge sensor based on Ge/Si heterostructure nanowires

Coupled electron spins in semiconductor double quantum dots hold promise as the basis for solid-state qubits. To date, most experiments have used III-V materials, in which coherence is limited by hyperfine interactions. Ge/Si heterostructure nanowires seem ideally suited to overcome this limitation: the predominance of spin-zero nuclei suppresses the hyperfine interaction and chemical synthesis creates a clean and defect-free system with highly controllable properties. Here we present a top gate-defined double quantum dot based on Ge/Si heterostructure nanowires with fully tunable coupling between the dots and to the leads. We also demonstrate a novel approach to charge sensing in a one-dimensional nanostructure by capacitively coupling the double dot to a single dot on an adjacent nanowire. The double quantum dot and integrated charge sensor serve as an essential building block required to form a solid-state spin qubit free of nuclear spin.Comment: Related work at http://marcuslab.harvard.edu and http://cmliris.harvard.ed

The African Women's Protocol: Bringing Attention to Reproductive Rights and the MDGs

Andrew Gibbs and colleagues discuss the African Women's Protocol, a framework for ensuring reproductive rights are supported throughout the continent and for supporting interventions to improve women's reproductive health, including the MDGs

Client preferences and acceptability for medical abortion and MVA as early pregnancy termination method in Northwest Ethiopia

<p>Abstract</p> <p>Background</p> <p>Increasing access to safe abortion services is the most effective way of preventing the burden of unsafe abortion, which is achieved by increasing safe choices for pregnancy termination. Medical abortion for termination of early abortion is said to safe, effective, and acceptable to women in several countries. In Ethiopia, however, medical methods have, until recently, never been used. For this reason it is important to assess women's preferences and the acceptability of medical abortion and manual vacuum aspiration (MVA) in the early first trimester pregnancy termination and factors affecting acceptability of medical and MVA abortion services.</p> <p>Methods</p> <p>A prospective study was conducted in two hospitals and two clinics from March 2009 to November 2009. The study population consisted of 414 subjects over the age of 18 with intrauterine pregnancies of up to 63 days' estimated gestation. Of these 251 subjects received mifepristone and misoprostol and 159 subjects received MVA. Questionnaires regarding expectations and experiences were administered before the abortion and at the 2-week follow-up visit.</p> <p>Results</p> <p>The study groups were similar with respect to age, marital status, educational status, religion and ethnicity. Their mean age was about 23, majority in both group completed secondary education and about half were married. Place of residence and duration of pregnancy were associated with method choice. Subjects undergoing medical abortions reported significantly greater satisfaction than those undergoing surgical abortions (91.2% vs 82.4%; <it>P </it>< .001). Of those women who had medical abortion, (83.3%) would choose the method again if needed, and (77.4%) of those who had MVA would also choose the method again. Ninety four percent of women who had medical abortion and 86.8% of those who had MVA would recommend the method to their friends.</p> <p>Conclusions</p> <p>Women receiving medical abortion were more satisfied with their method and more likely to choose the same method again than were subjects undergoing surgical abortion. We conclude that medical abortion can be used widely as an alternative method for early pregnancy termination.</p

Population policies and education: exploring the contradictions of neo-liberal globalisation

The world is increasingly characterised by profound income, health and social inequalities (Appadurai, 2000). In recent decades development initiatives aimed at reducing these inequalities have been situated in a context of increasing globalisation with a dominant neo-liberal economic orthodoxy. This paper argues that neo-liberal globalisation contains inherent contradictions regarding choice and uniformity. This is illustrated in this paper through an exploration of the impact of neo-liberal globalisation on population policies and programmes. The dominant neo-liberal economic ideology that has influenced development over the last few decades has often led to alternative global visions being overlooked. Many current population and development debates are characterised by polarised arguments with strongly opposing aims and views. This raises the challenge of finding alternatives situated in more middle ground that both identify and promote the socially positive elements of neo-liberalism and state intervention, but also to limit their worst excesses within the population field and more broadly. This paper concludes with a discussion outling the positive nature of middle ground and other possible alternatives

The Potential of Medical Abortion to Reduce Maternal Mortality in Africa: What Benefits for Tanzania and Ethiopia?

BACKGROUND: Unsafe abortion is estimated to account for 13% of maternal mortality globally. Medical abortion is a safe alternative. METHODS: By estimating mortality risks for unsafe and medical abortion and childbirth for Tanzania and Ethiopia, we modelled changes in maternal mortality that are achievable if unsafe abortion were replaced by medical abortion. We selected Ethiopia and Tanzania because of their high maternal mortality ratios (MMRatios) and contrasting situations regarding health care provision and abortion legislation. We focused on misoprostol-only regimens due to the drug's low cost and accessibility. We included the impact of medical abortion on women who would otherwise choose unsafe abortion and on women with unwanted/mistimed pregnancies who would otherwise carry to term. RESULTS: Thousands of lives could be saved each year in each country by implementing medical abortion using misoprostol (2122 in Tanzania and 2551 in Ethiopia assuming coverage equals family planning services levels: 56% for Tanzania, 31% for Ethiopia). Changes in MMRatios would be less pronounced because the intervention would also affect national birth rates. CONCLUSIONS: This is the first analysis of impact of medical abortion provision which takes into account additional potential users other than those currently using unsafe abortion. Thousands of women's lives could be saved, but this may not be reflected in as substantial changes in MMRatios because of medical abortion's demographic impact. Therefore policy makers must be aware of the inability of some traditional measures of maternal mortality to detect the real benefits offered by such an intervention

Estimating the costs for the treatment of abortion complications in two public referral hospitals: a cross-sectional study in Ouagadougou, Burkina Faso

Treatment costs of induced abortion complications can consume a substantial amount of hospital resources. This use of hospitals scarce resources to treat induced abortion complications may affect hospitals’ capacities to deliver other health care services. In spite of the importance of studying the burden of the treatment of induced abortion complications, few studies have been conducted to document the costs of treating abortion complications in Burkina Faso. Our objective was to estimate the costs of six abortion complications including incomplete abortion, hemorrhage, shock, infection/sepsis, cervix or vagina laceration, and uterus perforation treated in two public referral hospital facilities in Ouagadougou and the cost saving of providing safe abortion care services

Arbitrating abortion: sex-selection and care work among abortion providers in England

The UK’s on-going sex-selective abortion (SSA) controversy remains a major obstacle to the liberalization of national abortion governance, and is an issue broadly attributed to a “cultural” preference for sons among South Asian women. We conceptualize how healthcare professionals “arbitrate” requests for SSA by exploring the tension between its legal status and how requests are encountered by abortion providers. SSA is framed in this article as a legitimate care service that can support providers to meet the diverse reproductive health needs of women to the full extent of the law